xref: /netbsd/src/external/ibm-public/postfix/dist/src/smtp/smtp.c

/*        $NetBSD: smtp.c,v 1.14 2025/02/25 19:15:49 christos Exp $   */

/*++
/* NAME
/*        smtp, lmtp 8
/* SUMMARY
/*        Postfix SMTP+LMTP client
/* SYNOPSIS
/*        \fBsmtp\fR [generic Postfix daemon options] [flags=DORX]
/*
/*        \fBlmtp\fR [generic Postfix daemon options] [flags=DORX]
/* DESCRIPTION
/*        The Postfix SMTP+LMTP client implements the SMTP and LMTP mail
/*        delivery protocols. It processes message delivery requests from
/*        the queue manager. Each request specifies a queue file, a sender
/*        address, a domain or host to deliver to, and recipient information.
/*        This program expects to be run from the \fBmaster\fR(8) process
/*        manager. The process name, \fBsmtp\fR or \fBlmtp\fR, controls
/*        the protocol, and the names of the configuration parameters
/*        that will be used.
/*
/*        The SMTP+LMTP client updates the queue file and marks recipients
/*        as finished, or it informs the queue manager that delivery should
/*        be tried again at a later time. Delivery status reports are sent
/*        to the \fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) daemon as
/*        appropriate.
/*
/*        The server lookup strategy is different for SMTP and LMTP,
/*        as described in the sections "SMTP SERVER LOOKUP" and "LMTP
/*        SERVER LOOKUP".
/*
/*        After a successful mail transaction, a connection may be saved
/*        to the \fBscache\fR(8) connection cache server, so that it
/*        may be used by any SMTP+LMTP client for a subsequent transaction.
/*
/*        By default, connection caching is enabled temporarily for
/*        destinations that have a high volume of mail in the active
/*        queue. Connection caching can be enabled permanently for
/*        specific destinations.
/* SMTP SERVER LOOKUP
/* .ad
/* .fi
/*        The Postfix SMTP client supports multiple destinations
/*        separated by comma or whitespace (Postfix 3.5 and later).
/*        Each destination is tried in the specified order.
/*
/*        SMTP destinations have the following form:
/* .IP \fIdomainname\fR
/* .IP \fIdomainname\fR:\fIservice\fR
/*        Look up the mail exchangers for the specified domain, and
/*        connect to the specified service (default: \fBsmtp\fR).
/*        Optionally, mail exchangers may be looked up with SRV queries
/*        instead of MX; this requires that \fIservice\fR is given
/*        in symbolic form.
/* .IP [\fIhostname\fR]
/* .IP [\fIhostname\fR]:\fIservice\fR
/*        Look up the address(es) for the specified host, and connect to
/*        the specified service (default: \fBsmtp\fR).
/* .IP [\fIaddress\fR]
/* .IP [\fIaddress\fR]:\fIservice\fR
/*        Connect to the host at the specified address, and connect
/*        to the specified service (default: \fBsmtp\fR). An IPv6 address
/*        must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* LMTP SERVER LOOKUP
/* .ad
/* .fi
/*        The Postfix LMTP client supports multiple destinations
/*        separated by comma or whitespace (Postfix 3.5 and later).
/*        Each destination is tried in the specified order.
/*
/*        LMTP destinations have the following form:
/* .IP \fBunix\fR:\fIpathname\fR
/*        Connect to the local UNIX-domain server that is bound to the specified
/*        \fIpathname\fR. If the process runs chrooted, an absolute pathname
/*        is interpreted relative to the Postfix queue directory.
/* .IP \fBinet\fR:\fIdomainname\fR
/* .IP \fBinet\fR:\fIdomainname\fR:\fIservice\fR
/*        Look up the LMTP servers for the specified domain and service
/*        (default: \fBlmtp\fR).
/*        This form is supported when SRV lookups are enabled, and
/*        requires that \fIservice\fR is in symbolic form.
/* .IP \fBinet\fR:\fIhostname\fR
/* .IP \fBinet\fR:\fIhostname\fR:\fIservice\fR
/*        Look up the address(es) for the specified host, and connect to
/*        the specified service (default: \fBlmtp\fR). When SRV lookups
/*        are enabled, use the form \fB[\fIhostname\fB]\fR to force
/*        address lookups.
/* .IP \fBinet\fR:[\fIaddress\fR]
/* .IP \fBinet\fR:[\fIaddress\fR]:\fIservice\fR
/*        Connect to the specified local or remote host and service
/*        (default: \fBlmtp\fR).
/*        An IPv6 address must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* SINGLE-RECIPIENT DELIVERY
/* .ad
/* .fi
/*        By default, the Postfix SMTP+LMTP client delivers mail to
/*        multiple recipients per delivery request. This is undesirable
/*        when prepending a \fBDelivered-to:\fR or \fBX-Original-To:\fR
/*        message header. To prevent Postfix from sending multiple
/*        recipients per delivery request, specify
/* .sp
/* .nf
/*            \fItransport\fB_destination_recipient_limit = 1\fR
/* .fi
/*
/*        in the Postfix \fBmain.cf\fR file, where \fItransport\fR
/*        is the name in the first column of the Postfix \fBmaster.cf\fR
/*        entry for this mail delivery service.
/* COMMAND ATTRIBUTE SYNTAX
/* .ad
/* .fi
/* .IP "\fBflags=DORX\fR (optional)"
/*        Optional message processing flags.
/* .RS
/* .IP \fBD\fR
/*        Prepend a "\fBDelivered-To: \fIrecipient\fR" message header
/*        with the envelope recipient address. Note: for this to work,
/*        the \fItransport\fB_destination_recipient_limit\fR must be
/*        1 (see SINGLE-RECIPIENT DELIVERY above for details).
/* .sp
/*        The \fBD\fR flag also enforces loop detection: if a message
/*        already contains a \fBDelivered-To:\fR header with the same
/*        recipient address, then the message is returned as
/*        undeliverable. The address comparison is case insensitive.
/* .sp
/*        This feature is available as of Postfix 3.5.
/* .IP \fBO\fR
/*        Prepend an "\fBX-Original-To: \fIrecipient\fR" message
/*        header with the recipient address as given to Postfix. Note:
/*        for this to work, the
/*        \fItransport\fB_destination_recipient_limit\fR must be 1
/*        (see SINGLE-RECIPIENT DELIVERY above for details).
/* .sp
/*        This feature is available as of Postfix 3.5.
/* .IP \fBR\fR
/*        Prepend a "\fBReturn-Path: <\fIsender\fB>\fR" message header
/*        with the envelope sender address.
/* .sp
/*        This feature is available as of Postfix 3.5.
/* .IP \fBX\fR
/*        Indicates that the delivery is final. This flag affects
/*        the status reported in "success" DSN (delivery status
/*        notification) messages, and changes it from "relayed" into
/*        "delivered".
/* .sp
/*        This feature is available as of Postfix 3.5.
/* .RE
/* SECURITY
/* .ad
/* .fi
/*        The SMTP+LMTP client is moderately security-sensitive. It
/*        talks to SMTP or LMTP servers and to DNS servers on the
/*        network. The SMTP+LMTP client can be run chrooted at fixed
/*        low privilege.
/* STANDARDS
/*        RFC 821 (SMTP protocol)
/*        RFC 822 (ARPA Internet Text Messages)
/*        RFC 1651 (SMTP service extensions)
/*        RFC 1652 (8bit-MIME transport)
/*        RFC 1870 (Message Size Declaration)
/*        RFC 2033 (LMTP protocol)
/*        RFC 2034 (SMTP Enhanced Error Codes)
/*        RFC 2045 (MIME: Format of Internet Message Bodies)
/*        RFC 2046 (MIME: Media Types)
/*        RFC 2554 (AUTH command)
/*        RFC 2821 (SMTP protocol)
/*        RFC 2782 (SRV resource records)
/*        RFC 2920 (SMTP Pipelining)
/*        RFC 3207 (STARTTLS command)
/*        RFC 3461 (SMTP DSN Extension)
/*        RFC 3463 (Enhanced Status Codes)
/*        RFC 4954 (AUTH command)
/*        RFC 5321 (SMTP protocol)
/*        RFC 6531 (Internationalized SMTP)
/*        RFC 6533 (Internationalized Delivery Status Notifications)
/*        RFC 7672 (SMTP security via opportunistic DANE TLS)
/*        RFC 8689 (TLS-Required message header)
/* DIAGNOSTICS
/*        Problems and transactions are logged to \fBsyslogd\fR(8)
/*        or \fBpostlogd\fR(8).
/*        Corrupted message files are marked so that the queue manager can
/*        move them to the \fBcorrupt\fR queue for further inspection.
/*
/*        Depending on the setting of the \fBnotify_classes\fR parameter,
/*        the postmaster is notified of bounces, protocol problems, and of
/*        other trouble.
/* BUGS
/*        SMTP and LMTP connection reuse for TLS (without closing the
/*        SMTP or LMTP connection) is not supported before Postfix 3.4.
/*
/*        SMTP and LMTP connection reuse assumes that SASL credentials
/*        are valid for all destinations that map onto the same IP
/*        address and TCP port.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*        Postfix versions 2.3 and later implement the SMTP and LMTP
/*        client with the same program, and choose the protocol and
/*        configuration parameters based on the process name, \fBsmtp\fR
/*        or \fBlmtp\fR.
/*
/*        Most smtp_\fIxxx\fR configuration parameters have an
/*        lmtp_\fIxxx\fR "mirror" parameter for the equivalent LMTP
/*        feature. This document describes only those LMTP-related
/*        parameters that aren't simply "mirror" parameters.
/*
/*        Changes to \fBmain.cf\fR are picked up automatically, as \fBsmtp\fR(8)
/*        processes run for only a limited amount of time. Use the command
/*        "\fBpostfix reload\fR" to speed up a change.
/*
/*        The text below provides only a parameter summary. See
/*        \fBpostconf\fR(5) for more details including examples.
/* COMPATIBILITY CONTROLS
/* .ad
/* .fi
/* .IP "\fBignore_mx_lookup_error (no)\fR"
/*        Ignore DNS MX lookups that produce no response.
/* .IP "\fBsmtp_always_send_ehlo (yes)\fR"
/*        Always send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_never_send_ehlo (no)\fR"
/*        Never send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_defer_if_no_mx_address_found (no)\fR"
/*        Defer mail delivery when no MX record resolves to an IP address.
/* .IP "\fBsmtp_line_length_limit (998)\fR"
/*        The maximal length of message header and body lines that Postfix
/*        will send via SMTP.
/* .IP "\fBsmtp_pix_workaround_delay_time (10s)\fR"
/*        How long the Postfix SMTP client pauses before sending
/*        ".<CR><LF>" in order to work around the PIX firewall
/*        "<CR><LF>.<CR><LF>" bug.
/* .IP "\fBsmtp_pix_workaround_threshold_time (500s)\fR"
/*        How long a message must be queued before the Postfix SMTP client
/*        turns on the PIX firewall "<CR><LF>.<CR><LF>"
/*        bug workaround for delivery through firewalls with "smtp fixup"
/*        mode turned on.
/* .IP "\fBsmtp_pix_workarounds (disable_esmtp, delay_dotcrlf)\fR"
/*        A list that specifies zero or more workarounds for CISCO PIX
/*        firewall bugs.
/* .IP "\fBsmtp_pix_workaround_maps (empty)\fR"
/*        Lookup tables, indexed by the remote SMTP server address, with
/*        per-destination workarounds for CISCO PIX firewall bugs.
/* .IP "\fBsmtp_quote_rfc821_envelope (yes)\fR"
/*        Quote addresses in Postfix SMTP client MAIL FROM and RCPT TO commands
/*        as required
/*        by RFC 5321.
/* .IP "\fBsmtp_reply_filter (empty)\fR"
/*        A mechanism to transform replies from remote SMTP servers one
/*        line at a time.
/* .IP "\fBsmtp_skip_5xx_greeting (yes)\fR"
/*        Skip remote SMTP servers that greet with a 5XX status code.
/* .IP "\fBsmtp_skip_quit_response (yes)\fR"
/*        Do not wait for the response to the SMTP QUIT command.
/* .PP
/*        Available in Postfix version 2.0 and earlier:
/* .IP "\fBsmtp_skip_4xx_greeting (yes)\fR"
/*        Skip SMTP servers that greet with a 4XX status code (go away, try
/*        again later).
/* .PP
/*        Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_discard_ehlo_keyword_address_maps (empty)\fR"
/*        Lookup tables, indexed by the remote SMTP server address, with
/*        case insensitive lists of EHLO keywords (pipelining, starttls, auth,
/*        etc.) that the Postfix SMTP client will ignore in the EHLO response from a
/*        remote SMTP server.
/* .IP "\fBsmtp_discard_ehlo_keywords (empty)\fR"
/*        A case insensitive list of EHLO keywords (pipelining, starttls,
/*        auth, etc.) that the Postfix SMTP client will ignore in the EHLO
/*        response from a remote SMTP server.
/* .IP "\fBsmtp_generic_maps (empty)\fR"
/*        Optional lookup tables that perform address rewriting in the
/*        Postfix SMTP client, typically to transform a locally valid address into
/*        a globally valid address when sending mail across the Internet.
/* .PP
/*        Available in Postfix version 2.2.9 and later:
/* .IP "\fBsmtp_cname_overrides_servername (version dependent)\fR"
/*        When the remote SMTP servername is a DNS CNAME, replace the
/*        servername with the result from CNAME expansion for the purpose of
/*        logging, SASL password lookup, TLS
/*        policy decisions, or TLS certificate verification.
/* .PP
/*        Available in Postfix version 2.3 and later:
/* .IP "\fBlmtp_discard_lhlo_keyword_address_maps (empty)\fR"
/*        Lookup tables, indexed by the remote LMTP server address, with
/*        case insensitive lists of LHLO keywords (pipelining, starttls,
/*        auth, etc.) that the Postfix LMTP client will ignore in the LHLO
/*        response
/*        from a remote LMTP server.
/* .IP "\fBlmtp_discard_lhlo_keywords (empty)\fR"
/*        A case insensitive list of LHLO keywords (pipelining, starttls,
/*        auth, etc.) that the Postfix LMTP client will ignore in the LHLO
/*        response
/*        from a remote LMTP server.
/* .PP
/*        Available in Postfix version 2.4.4 and later:
/* .IP "\fBsend_cyrus_sasl_authzid (no)\fR"
/*        When authenticating to a remote SMTP or LMTP server with the
/*        default setting "no", send no SASL authoriZation ID (authzid); send
/*        only the SASL authentiCation ID (authcid) plus the authcid's password.
/* .PP
/*        Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_header_checks (empty)\fR"
/*        Restricted \fBheader_checks\fR(5) tables for the Postfix SMTP client.
/* .IP "\fBsmtp_mime_header_checks (empty)\fR"
/*        Restricted \fBmime_header_checks\fR(5) tables for the Postfix SMTP
/*        client.
/* .IP "\fBsmtp_nested_header_checks (empty)\fR"
/*        Restricted \fBnested_header_checks\fR(5) tables for the Postfix SMTP
/*        client.
/* .IP "\fBsmtp_body_checks (empty)\fR"
/*        Restricted \fBbody_checks\fR(5) tables for the Postfix SMTP client.
/* .PP
/*        Available in Postfix version 2.6 and later:
/* .IP "\fBtcp_windowsize (0)\fR"
/*        An optional workaround for routers that break TCP window scaling.
/* .PP
/*        Available in Postfix version 2.8 and later:
/* .IP "\fBsmtp_dns_resolver_options (empty)\fR"
/*        DNS Resolver options for the Postfix SMTP client.
/* .PP
/*        Available in Postfix version 2.9 - 3.6:
/* .IP "\fBsmtp_per_record_deadline (no)\fR"
/*        Change the behavior of the smtp_*_timeout time limits, from a
/*        time limit per read or write system call, to a time limit to send
/*        or receive a complete record (an SMTP command line, SMTP response
/*        line, SMTP message content line, or TLS protocol message).
/* .PP
/*        Available in Postfix version 2.9 and later:
/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR"
/*        Whether or not to append the "AUTH=<>" option to the MAIL
/*        FROM command in SASL-authenticated SMTP sessions.
/* .PP
/*        Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_dns_support_level (empty)\fR"
/*        Level of DNS support in the Postfix SMTP client.
/* .PP
/*        Available in Postfix version 3.0 and later:
/* .IP "\fBsmtp_delivery_status_filter ($default_delivery_status_filter)\fR"
/*        Optional filter for the \fBsmtp\fR(8) delivery agent to change the
/*        delivery status code or explanatory text of successful or unsuccessful
/*        deliveries.
/* .IP "\fBsmtp_dns_reply_filter (empty)\fR"
/*        Optional filter for Postfix SMTP client DNS lookup results.
/* .PP
/*        Available in Postfix version 3.3 and later:
/* .IP "\fBsmtp_balance_inet_protocols (yes)\fR"
/*        When a remote destination resolves to a combination of IPv4 and
/*        IPv6 addresses, ensure that the Postfix SMTP client can try both
/*        address types before it runs into the smtp_mx_address_limit.
/* .PP
/*        Available in Postfix 3.5 and later:
/* .IP "\fBinfo_log_address_format (external)\fR"
/*        The email address form that will be used in non-debug logging
/*        (info, warning, etc.).
/* .PP
/*        Available in Postfix 3.6 and later:
/* .IP "\fBdnssec_probe (ns:.)\fR"
/*        The DNS query type (default: "ns") and DNS query name (default:
/*        ".") that Postfix may use to determine whether DNSSEC validation
/*        is available.
/* .IP "\fBknown_tcp_ports (lmtp=24, smtp=25, smtps=submissions=465, submission=587)\fR"
/*        Optional setting that avoids lookups in the \fBservices\fR(5) database.
/* .PP
/*        Available in Postfix version 3.7 and later:
/* .IP "\fBsmtp_per_request_deadline (no)\fR"
/*        Change the behavior of the smtp_*_timeout time limits, from a
/*        time limit per plaintext or TLS read or write call, to a combined
/*        time limit for sending a complete SMTP request and for receiving a
/*        complete SMTP response.
/* .IP "\fBsmtp_min_data_rate (500)\fR"
/*        The minimum plaintext data transfer rate in bytes/second for
/*        DATA requests, when deadlines are enabled with smtp_per_request_deadline.
/* .IP "\fBheader_from_format (standard)\fR"
/*        The format of the Postfix-generated \fBFrom:\fR header.
/* .PP
/*        Available in Postfix version 3.8 and later:
/* .IP "\fBuse_srv_lookup (empty)\fR"
/*        Enables discovery for the specified service(s) using DNS SRV
/*        records.
/* .IP "\fBignore_srv_lookup_error (no)\fR"
/*        When SRV record lookup fails, fall back to MX or IP address
/*        lookup as if SRV record lookup was not enabled.
/* .IP "\fBallow_srv_lookup_fallback (no)\fR"
/*        When SRV record lookup fails or no SRV record exists, fall back
/*        to MX or IP address lookup as if SRV record lookup was not enabled.
/* MIME PROCESSING CONTROLS
/* .ad
/* .fi
/*        Available in Postfix version 2.0 and later:
/* .IP "\fBdisable_mime_output_conversion (no)\fR"
/*        Disable the conversion of 8BITMIME format to 7BIT format.
/* .IP "\fBmime_boundary_length_limit (2048)\fR"
/*        The maximal length of MIME multipart boundary strings.
/* .IP "\fBmime_nesting_limit (100)\fR"
/*        The maximal recursion level that the MIME processor will handle.
/* EXTERNAL CONTENT INSPECTION CONTROLS
/* .ad
/* .fi
/*        Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_send_xforward_command (no)\fR"
/*        Send the non-standard XFORWARD command when the Postfix SMTP server
/*        EHLO response announces XFORWARD support.
/* SASL AUTHENTICATION CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_sasl_auth_enable (no)\fR"
/*        Enable SASL authentication in the Postfix SMTP client.
/* .IP "\fBsmtp_sasl_password_maps (empty)\fR"
/*        Optional Postfix SMTP client lookup tables with one username:password
/*        entry per sender, remote hostname or next-hop domain.
/* .IP "\fBsmtp_sasl_security_options (noplaintext, noanonymous)\fR"
/*        Postfix SMTP client SASL security options; as of Postfix 2.3
/*        the list of available
/*        features depends on the SASL client implementation that is selected
/*        with \fBsmtp_sasl_type\fR.
/* .PP
/*        Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_sasl_mechanism_filter (empty)\fR"
/*        If non-empty, a Postfix SMTP client filter for the remote SMTP
/*        server's list of offered SASL mechanisms.
/* .PP
/*        Available in Postfix version 2.3 and later:
/* .IP "\fBsmtp_sender_dependent_authentication (no)\fR"
/*        Enable sender-dependent authentication in the Postfix SMTP client; this is
/*        available only with SASL authentication, and disables SMTP connection
/*        caching to ensure that mail from different senders will use the
/*        appropriate credentials.
/* .IP "\fBsmtp_sasl_path (empty)\fR"
/*        Implementation-specific information that the Postfix SMTP client
/*        passes through to
/*        the SASL plug-in implementation that is selected with
/*        \fBsmtp_sasl_type\fR.
/* .IP "\fBsmtp_sasl_type (cyrus)\fR"
/*        The SASL plug-in type that the Postfix SMTP client should use
/*        for authentication.
/* .PP
/*        Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_sasl_auth_cache_name (empty)\fR"
/*        An optional table to prevent repeated SASL authentication
/*        failures with the same remote SMTP server hostname, username and
/*        password.
/* .IP "\fBsmtp_sasl_auth_cache_time (90d)\fR"
/*        The maximal age of an smtp_sasl_auth_cache_name entry before it
/*        is removed.
/* .IP "\fBsmtp_sasl_auth_soft_bounce (yes)\fR"
/*        When a remote SMTP server rejects a SASL authentication request
/*        with a 535 reply code, defer mail delivery instead of returning
/*        mail as undeliverable.
/* .PP
/*        Available in Postfix version 2.9 and later:
/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR"
/*        Whether or not to append the "AUTH=<>" option to the MAIL
/*        FROM command in SASL-authenticated SMTP sessions.
/* .PP
/*        Available in Postfix version 3.9 and later:
/* .IP "\fBsmtp_sasl_password_result_delimiter (:)\fR"
/*        The delimiter between username and password in sasl_passwd_maps lookup
/*        results.
/* STARTTLS SUPPORT CONTROLS
/* .ad
/* .fi
/*        Detailed information about STARTTLS configuration may be found
/*        in the TLS_README document.
/* .IP "\fBsmtp_tls_security_level (empty)\fR"
/*        The default SMTP TLS security level for the Postfix SMTP client.
/* .IP "\fBsmtp_sasl_tls_security_options ($smtp_sasl_security_options)\fR"
/*        The SASL authentication security options that the Postfix SMTP
/*        client uses for TLS encrypted SMTP sessions.
/* .IP "\fBsmtp_starttls_timeout (300s)\fR"
/*        Time limit for Postfix SMTP client write and read operations
/*        during TLS startup and shutdown handshake procedures.
/* .IP "\fBsmtp_tls_CAfile (empty)\fR"
/*        A file containing CA certificates of root CAs trusted to sign
/*        either remote SMTP server certificates or intermediate CA certificates.
/* .IP "\fBsmtp_tls_CApath (empty)\fR"
/*        Directory with PEM format Certification Authority certificates
/*        that the Postfix SMTP client uses to verify a remote SMTP server
/*        certificate.
/* .IP "\fBsmtp_tls_cert_file (empty)\fR"
/*        File with the Postfix SMTP client RSA certificate in PEM format.
/* .IP "\fBsmtp_tls_mandatory_ciphers (medium)\fR"
/*        The minimum TLS cipher grade that the Postfix SMTP client will
/*        use with
/*        mandatory TLS encryption.
/* .IP "\fBsmtp_tls_exclude_ciphers (empty)\fR"
/*        List of ciphers or cipher types to exclude from the Postfix
/*        SMTP client cipher
/*        list at all TLS security levels.
/* .IP "\fBsmtp_tls_mandatory_exclude_ciphers (empty)\fR"
/*        Additional list of ciphers or cipher types to exclude from the
/*        Postfix SMTP client cipher list at mandatory TLS security levels.
/* .IP "\fBsmtp_tls_dcert_file (empty)\fR"
/*        File with the Postfix SMTP client DSA certificate in PEM format.
/* .IP "\fBsmtp_tls_dkey_file ($smtp_tls_dcert_file)\fR"
/*        File with the Postfix SMTP client DSA private key in PEM format.
/* .IP "\fBsmtp_tls_key_file ($smtp_tls_cert_file)\fR"
/*        File with the Postfix SMTP client RSA private key in PEM format.
/* .IP "\fBsmtp_tls_loglevel (0)\fR"
/*        Enable additional Postfix SMTP client logging of TLS activity.
/* .IP "\fBsmtp_tls_note_starttls_offer (no)\fR"
/*        Log the hostname of a remote SMTP server that offers STARTTLS,
/*        when TLS is not already enabled for that server.
/* .IP "\fBsmtp_tls_policy_maps (empty)\fR"
/*        Optional lookup tables with the Postfix SMTP client TLS security
/*        policy by next-hop destination; when a non-empty value is specified,
/*        this overrides the obsolete smtp_tls_per_site parameter.
/* .IP "\fBsmtp_tls_mandatory_protocols (see 'postconf -d' output)\fR"
/*        TLS protocols that the Postfix SMTP client will use with mandatory
/*        TLS encryption.
/* .IP "\fBsmtp_tls_scert_verifydepth (9)\fR"
/*        The verification depth for remote SMTP server certificates.
/* .IP "\fBsmtp_tls_secure_cert_match (nexthop, dot-nexthop)\fR"
/*        How the Postfix SMTP client verifies the server certificate
/*        peername for the "secure" TLS security level.
/* .IP "\fBsmtp_tls_session_cache_database (empty)\fR"
/*        Name of the file containing the optional Postfix SMTP client
/*        TLS session cache.
/* .IP "\fBsmtp_tls_session_cache_timeout (3600s)\fR"
/*        The expiration time of Postfix SMTP client TLS session cache
/*        information.
/* .IP "\fBsmtp_tls_verify_cert_match (hostname)\fR"
/*        How the Postfix SMTP client verifies the server certificate
/*        peername for the
/*        "verify" TLS security level.
/* .IP "\fBtls_daemon_random_bytes (32)\fR"
/*        The number of pseudo-random bytes that an \fBsmtp\fR(8) or \fBsmtpd\fR(8)
/*        process requests from the \fBtlsmgr\fR(8) server in order to seed its
/*        internal pseudo random number generator (PRNG).
/* .IP "\fBtls_high_cipherlist (see 'postconf -d' output)\fR"
/*        The OpenSSL cipherlist for "high" grade ciphers.
/* .IP "\fBtls_medium_cipherlist (see 'postconf -d' output)\fR"
/*        The OpenSSL cipherlist for "medium" or higher grade ciphers.
/* .IP "\fBtls_null_cipherlist (eNULL:!aNULL)\fR"
/*        The OpenSSL cipherlist for "NULL" grade ciphers that provide
/*        authentication without encryption.
/* .PP
/*        Available in in Postfix version 2.3..3.7:
/* .IP "\fBtls_low_cipherlist (see 'postconf -d' output)\fR"
/*        The OpenSSL cipherlist for "low" or higher grade ciphers.
/* .IP "\fBtls_export_cipherlist (see 'postconf -d' output)\fR"
/*        The OpenSSL cipherlist for "export" or higher grade ciphers.
/* .PP
/*        Available in Postfix version 2.4 and later:
/* .IP "\fBsmtp_sasl_tls_verified_security_options ($smtp_sasl_tls_security_options)\fR"
/*        The SASL authentication security options that the Postfix SMTP
/*        client uses for TLS encrypted SMTP sessions with a verified server
/*        certificate.
/* .PP
/*        Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_tls_fingerprint_cert_match (empty)\fR"
/*        List of acceptable remote SMTP server certificate fingerprints for
/*        the "fingerprint" TLS security level (\fBsmtp_tls_security_level\fR =
/*        fingerprint).
/* .IP "\fBsmtp_tls_fingerprint_digest (see 'postconf -d' output)\fR"
/*        The message digest algorithm used to construct remote SMTP server
/*        certificate fingerprints.
/* .PP
/*        Available in Postfix version 2.6 and later:
/* .IP "\fBsmtp_tls_protocols (see 'postconf -d' output)\fR"
/*        TLS protocols that the Postfix SMTP client will use with
/*        opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_ciphers (medium)\fR"
/*        The minimum TLS cipher grade that the Postfix SMTP client
/*        will use with opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_eccert_file (empty)\fR"
/*        File with the Postfix SMTP client ECDSA certificate in PEM format.
/* .IP "\fBsmtp_tls_eckey_file ($smtp_tls_eccert_file)\fR"
/*        File with the Postfix SMTP client ECDSA private key in PEM format.
/* .PP
/*        Available in Postfix version 2.7 and later:
/* .IP "\fBsmtp_tls_block_early_mail_reply (no)\fR"
/*        Try to detect a mail hijacking attack based on a TLS protocol
/*        vulnerability (CVE-2009-3555), where an attacker prepends malicious
/*        HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client TLS session.
/* .PP
/*        Available in Postfix version 2.8 and later:
/* .IP "\fBtls_disable_workarounds (see 'postconf -d' output)\fR"
/*        List or bit-mask of OpenSSL bug work-arounds to disable.
/* .PP
/*        Available in Postfix version 2.11-3.1:
/* .IP "\fBtls_dane_digest_agility (on)\fR"
/*        Configure RFC7671 DANE TLSA digest algorithm agility.
/* .IP "\fBtls_dane_trust_anchor_digest_enable (yes)\fR"
/*        Enable support for RFC 6698 (DANE TLSA) DNS records that contain
/*        digests of trust-anchors with certificate usage "2".
/* .PP
/*        Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_tls_trust_anchor_file (empty)\fR"
/*        Zero or more PEM-format files with trust-anchor certificates
/*        and/or public keys.
/* .IP "\fBsmtp_tls_force_insecure_host_tlsa_lookup (no)\fR"
/*        Lookup the associated DANE TLSA RRset even when a hostname is
/*        not an alias and its address records lie in an unsigned zone.
/* .IP "\fBtlsmgr_service_name (tlsmgr)\fR"
/*        The name of the \fBtlsmgr\fR(8) service entry in master.cf.
/* .PP
/*        Available in Postfix version 3.0 and later:
/* .IP "\fBsmtp_tls_wrappermode (no)\fR"
/*        Request that the Postfix SMTP client connects using the
/*        SUBMISSIONS (formerly called SMTPS) protocol instead of using the
/*        STARTTLS command.
/* .PP
/*        Available in Postfix version 3.1 and later:
/* .IP "\fBsmtp_tls_dane_insecure_mx_policy (dane)\fR"
/*        The TLS policy for MX hosts with "secure" TLSA records when the
/*        nexthop destination security level is \fBdane\fR, but the MX
/*        record was found via an "insecure" MX lookup.
/* .PP
/*        Available in Postfix version 3.2 and later:
/* .IP "\fBtls_eecdh_auto_curves (see 'postconf -d' output)\fR"
/*        The prioritized list of elliptic curves, that should be enabled in the
/*        Postfix SMTP client and server.
/* .PP
/*        Available in Postfix version 3.4 and later:
/* .IP "\fBsmtp_tls_connection_reuse (no)\fR"
/*        Try to make multiple deliveries per TLS-encrypted connection.
/* .IP "\fBsmtp_tls_chain_files (empty)\fR"
/*        List of one or more PEM files, each holding one or more private keys
/*        directly followed by a corresponding certificate chain.
/* .IP "\fBsmtp_tls_servername (empty)\fR"
/*        Optional name to send to the remote SMTP server in the TLS Server
/*        Name Indication (SNI) extension.
/* .PP
/*        Available in Postfix 3.5, 3.4.6, 3.3.5, 3.2.10, 3.1.13 and later:
/* .IP "\fBtls_fast_shutdown_enable (yes)\fR"
/*        A workaround for implementations that hang Postfix while shutting
/*        down a TLS session, until Postfix times out.
/* .PP
/*        Available in Postfix version 3.8 and later:
/* .IP "\fBtls_ffdhe_auto_groups (see 'postconf -d' output)\fR"
/*        The prioritized list of finite-field Diffie-Hellman ephemeral
/*        (FFDHE) key exchange groups supported by the Postfix SMTP client and
/*        server.
/* .PP
/*        Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later:
/* .IP "\fBtls_config_file (default)\fR"
/*        Optional configuration file with baseline OpenSSL settings.
/* .IP "\fBtls_config_name (empty)\fR"
/*        The application name passed by Postfix to OpenSSL library
/*        initialization functions.
/* .PP
/*        Available in Postfix version 3.9 and later:
/* .IP "\fBsmtp_tls_enable_rpk (no)\fR"
/*        Request that remote SMTP servers send an RFC7250 raw public key
/*        instead of an X.509 certificate.
/* .PP
/*        Available in Postfix version 3.10 and later:
/* .IP "\fBsmtp_tlsrpt_enable (no)\fR"
/*        Enable support for RFC 8460 TLSRPT notifications.
/* .IP "\fBsmtp_tlsrpt_socket_name (empty)\fR"
/*        The pathname of a UNIX-domain datagram socket that is managed
/*        by a local TLSRPT reporting service.
/* .IP "\fBsmtp_tlsrpt_skip_reused_handshakes (yes)\fR"
/*        Do not report the TLSRPT status for TLS protocol handshakes
/*        that reuse a previously-negotiated TLS session (there is no new
/*        information to report).
/* .IP "\fBtls_required_enable (yes)\fR"
/*        Enable support for the "TLS-Required: no" message header, defined
/*        in RFC 8689.
/* OBSOLETE STARTTLS CONTROLS
/* .ad
/* .fi
/*        The following configuration parameters exist for compatibility
/*        with Postfix versions before 2.3. Support for these will
/*        be removed in a future release.
/* .IP "\fBsmtp_use_tls (no)\fR"
/*        Opportunistic mode: use TLS when a remote SMTP server announces
/*        STARTTLS support, otherwise send the mail in the clear.
/* .IP "\fBsmtp_enforce_tls (no)\fR"
/*        Enforcement mode: require that remote SMTP servers use TLS
/*        encryption, and never send mail in the clear.
/* .IP "\fBsmtp_tls_enforce_peername (yes)\fR"
/*        With mandatory TLS encryption, require that the remote SMTP
/*        server hostname matches the information in the remote SMTP server
/*        certificate.
/* .IP "\fBsmtp_tls_per_site (empty)\fR"
/*        Optional lookup tables with the Postfix SMTP client TLS usage
/*        policy by next-hop destination and by remote SMTP server hostname.
/* .IP "\fBsmtp_tls_cipherlist (empty)\fR"
/*        Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS
/*        cipher list.
/* RESOURCE AND RATE CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_connect_timeout (30s)\fR"
/*        The Postfix SMTP client time limit for completing a TCP connection, or
/*        zero (use the operating system built-in time limit).
/* .IP "\fBsmtp_helo_timeout (300s)\fR"
/*        The Postfix SMTP client time limit for sending the HELO or EHLO command,
/*        and for receiving the initial remote SMTP server response.
/* .IP "\fBlmtp_lhlo_timeout (300s)\fR"
/*        The Postfix LMTP client time limit for sending the LHLO command,
/*        and for receiving the initial remote LMTP server response.
/* .IP "\fBsmtp_xforward_timeout (300s)\fR"
/*        The Postfix SMTP client time limit for sending the XFORWARD command,
/*        and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_mail_timeout (300s)\fR"
/*        The Postfix SMTP client time limit for sending the MAIL FROM command,
/*        and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_rcpt_timeout (300s)\fR"
/*        The Postfix SMTP client time limit for sending the SMTP RCPT TO
/*        command, and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_data_init_timeout (120s)\fR"
/*        The Postfix SMTP client time limit for sending the SMTP DATA command,
/*        and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_data_xfer_timeout (180s)\fR"
/*        The Postfix SMTP client time limit for sending the SMTP message content.
/* .IP "\fBsmtp_data_done_timeout (600s)\fR"
/*        The Postfix SMTP client time limit for sending the SMTP ".", and
/*        for receiving the remote SMTP server response.
/* .IP "\fBsmtp_quit_timeout (300s)\fR"
/*        The Postfix SMTP client time limit for sending the QUIT command,
/*        and for receiving the remote SMTP server response.
/* .PP
/*        Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_mx_address_limit (5)\fR"
/*        The maximal number of MX (mail exchanger) IP addresses that can
/*        result from Postfix SMTP client mail exchanger lookups, or zero (no
/*        limit).
/* .IP "\fBsmtp_mx_session_limit (2)\fR"
/*        The maximal number of SMTP sessions per delivery request before
/*        the Postfix SMTP client
/*        gives up or delivers to a fall-back relay host, or zero (no
/*        limit).
/* .IP "\fBsmtp_rset_timeout (20s)\fR"
/*        The Postfix SMTP client time limit for sending the RSET command,
/*        and for receiving the remote SMTP server response.
/* .PP
/*        Available in Postfix version 2.2 and earlier:
/* .IP "\fBlmtp_cache_connection (yes)\fR"
/*        Keep Postfix LMTP client connections open for up to $max_idle
/*        seconds.
/* .PP
/*        Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_connection_cache_destinations (empty)\fR"
/*        Permanently enable SMTP connection caching for the specified
/*        destinations.
/* .IP "\fBsmtp_connection_cache_on_demand (yes)\fR"
/*        Temporarily enable SMTP connection caching while a destination
/*        has a high volume of mail in the active queue.
/* .IP "\fBsmtp_connection_reuse_time_limit (300s)\fR"
/*        The amount of time during which Postfix will use an SMTP
/*        connection repeatedly.
/* .IP "\fBsmtp_connection_cache_time_limit (2s)\fR"
/*        When SMTP connection caching is enabled, the amount of time that
/*        an unused SMTP client socket is kept open before it is closed.
/* .PP
/*        Available in Postfix version 2.3 and later:
/* .IP "\fBconnection_cache_protocol_timeout (5s)\fR"
/*        Time limit for connection cache connect, send or receive
/*        operations.
/* .PP
/*        Available in Postfix version 2.9 - 3.6:
/* .IP "\fBsmtp_per_record_deadline (no)\fR"
/*        Change the behavior of the smtp_*_timeout time limits, from a
/*        time limit per read or write system call, to a time limit to send
/*        or receive a complete record (an SMTP command line, SMTP response
/*        line, SMTP message content line, or TLS protocol message).
/* .PP
/*        Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_connection_reuse_count_limit (0)\fR"
/*        When SMTP connection caching is enabled, the number of times
/*        that an SMTP session may be reused before it is closed, or zero (no
/*        limit).
/* .PP
/*        Available in Postfix version 3.4 and later:
/* .IP "\fBsmtp_tls_connection_reuse (no)\fR"
/*        Try to make multiple deliveries per TLS-encrypted connection.
/* .PP
/*        Available in Postfix version 3.7 and later:
/* .IP "\fBsmtp_per_request_deadline (no)\fR"
/*        Change the behavior of the smtp_*_timeout time limits, from a
/*        time limit per plaintext or TLS read or write call, to a combined
/*        time limit for sending a complete SMTP request and for receiving a
/*        complete SMTP response.
/* .IP "\fBsmtp_min_data_rate (500)\fR"
/*        The minimum plaintext data transfer rate in bytes/second for
/*        DATA requests, when deadlines are enabled with smtp_per_request_deadline.
/* .PP
/*        Implemented in the qmgr(8) daemon:
/* .IP "\fBtransport_destination_concurrency_limit ($default_destination_concurrency_limit)\fR"
/*        A transport-specific override for the
/*        default_destination_concurrency_limit parameter value, where
/*        \fItransport\fR is the master.cf name of the message delivery
/*        transport.
/* .IP "\fBtransport_destination_recipient_limit ($default_destination_recipient_limit)\fR"
/*        A transport-specific override for the
/*        default_destination_recipient_limit parameter value, where
/*        \fItransport\fR is the master.cf name of the message delivery
/*        transport.
/* SMTPUTF8 CONTROLS
/* .ad
/* .fi
/*        Preliminary SMTPUTF8 support is introduced with Postfix 3.0.
/* .IP "\fBsmtputf8_enable (yes)\fR"
/*        Enable preliminary SMTPUTF8 support for the protocols described
/*        in RFC 6531, RFC 6532, and RFC 6533.
/* .IP "\fBsmtputf8_autodetect_classes (sendmail, verify)\fR"
/*        Detect that a message requires SMTPUTF8 support for the specified
/*        mail origin classes.
/* .PP
/*        Available in Postfix version 3.2 and later:
/* .IP "\fBenable_idna2003_compatibility (no)\fR"
/*        Enable 'transitional' compatibility between IDNA2003 and IDNA2008,
/*        when converting UTF-8 domain names to/from the ASCII form that is
/*        used for DNS lookups.
/* TROUBLE SHOOTING CONTROLS
/* .ad
/* .fi
/* .IP "\fBdebug_peer_level (2)\fR"
/*        The increment in verbose logging level when a nexthop destination,
/*        remote client or server name or network address matches a pattern
/*        given with the debug_peer_list parameter.
/* .IP "\fBdebug_peer_list (empty)\fR"
/*        Optional list of nexthop destination, remote client or server
/*        name or network address patterns that, if matched, cause the verbose
/*        logging level to increase by the amount specified in $debug_peer_level.
/* .IP "\fBerror_notice_recipient (postmaster)\fR"
/*        The recipient of postmaster notifications about mail delivery
/*        problems that are caused by policy, resource, software or protocol
/*        errors.
/* .IP "\fBinternal_mail_filter_classes (empty)\fR"
/*        What categories of Postfix-generated mail are subject to
/*        before-queue content inspection by non_smtpd_milters, header_checks
/*        and body_checks.
/* .IP "\fBnotify_classes (resource, software)\fR"
/*        The list of error classes that are reported to the postmaster.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBbest_mx_transport (empty)\fR"
/*        Where the Postfix SMTP client should deliver mail when it detects
/*        a "mail loops back to myself" error condition.
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*        The default location of the Postfix main.cf and master.cf
/*        configuration files.
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*        How much time a Postfix daemon process may take to handle a
/*        request before it is terminated by a built-in watchdog timer.
/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
/*        The maximal number of digits after the decimal point when logging
/*        delay values.
/* .IP "\fBdisable_dns_lookups (no)\fR"
/*        Disable DNS lookups in the Postfix SMTP and LMTP clients.
/* .IP "\fBinet_interfaces (all)\fR"
/*        The local network interface addresses that this mail system
/*        receives mail on.
/* .IP "\fBinet_protocols (see 'postconf -d' output)\fR"
/*        The Internet protocols Postfix will attempt to use when making
/*        or accepting connections.
/* .IP "\fBipc_timeout (3600s)\fR"
/*        The time limit for sending or receiving information over an internal
/*        communication channel.
/* .IP "\fBlmtp_assume_final (no)\fR"
/*        When a remote LMTP server announces no DSN support, assume that
/*        the
/*        server performs final delivery, and send "delivered" delivery status
/*        notifications instead of "relayed".
/* .IP "\fBlmtp_tcp_port (24)\fR"
/*        The default TCP port that the Postfix LMTP client connects to.
/* .IP "\fBmax_idle (100s)\fR"
/*        The maximum amount of time that an idle Postfix daemon process waits
/*        for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*        The maximal number of incoming connections that a Postfix daemon
/*        process will service before terminating voluntarily.
/* .IP "\fBprocess_id (read-only)\fR"
/*        The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*        The process name of a Postfix command or daemon process.
/* .IP "\fBproxy_interfaces (empty)\fR"
/*        The remote network interface addresses that this mail system receives mail
/*        on by way of a proxy or network address translation unit.
/* .IP "\fBsmtp_address_preference (any)\fR"
/*        The address type ("ipv6", "ipv4" or "any") that the Postfix
/*        SMTP client will try first, when a destination has IPv6 and IPv4
/*        addresses with equal MX preference.
/* .IP "\fBsmtp_bind_address (empty)\fR"
/*        An optional numerical network address that the Postfix SMTP client
/*        should bind to when making an IPv4 connection.
/* .IP "\fBsmtp_bind_address6 (empty)\fR"
/*        An optional numerical network address that the Postfix SMTP client
/*        should bind to when making an IPv6 connection.
/* .IP "\fBsmtp_helo_name ($myhostname)\fR"
/*        The hostname to send in the SMTP HELO or EHLO command.
/* .IP "\fBlmtp_lhlo_name ($myhostname)\fR"
/*        The hostname to send in the LMTP LHLO command.
/* .IP "\fBsmtp_host_lookup (dns)\fR"
/*        What mechanisms the Postfix SMTP client uses to look up a host's
/*        IP address.
/* .IP "\fBsmtp_randomize_addresses (yes)\fR"
/*        Randomize the order of equal-preference MX host addresses.
/* .IP "\fBsyslog_facility (mail)\fR"
/*        The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/*        A prefix that is prepended to the process name in syslog
/*        records, so that, for example, "smtpd" becomes "prefix/smtpd".
/* .PP
/*        Available with Postfix 2.2 and earlier:
/* .IP "\fBfallback_relay (empty)\fR"
/*        Optional list of relay hosts for SMTP destinations that can't be
/*        found or that are unreachable.
/* .PP
/*        Available with Postfix 2.3 and later:
/* .IP "\fBsmtp_fallback_relay ($fallback_relay)\fR"
/*        Optional list of relay destinations that will be used when an
/*        SMTP destination is not found, or when delivery fails due to a
/*        non-permanent error.
/* .PP
/*        Available with Postfix 3.0 and later:
/* .IP "\fBsmtp_address_verify_target (rcpt)\fR"
/*        In the context of email address verification, the SMTP protocol
/*        stage that determines whether an email address is deliverable.
/* .PP
/*        Available with Postfix 3.1 and later:
/* .IP "\fBlmtp_fallback_relay (empty)\fR"
/*        Optional list of relay hosts for LMTP destinations that can't be
/*        found or that are unreachable.
/* .PP
/*        Available with Postfix 3.2 and later:
/* .IP "\fBsmtp_tcp_port (smtp)\fR"
/*        The default TCP port that the Postfix SMTP client connects to.
/* .PP
/*        Available in Postfix 3.3 and later:
/* .IP "\fBservice_name (read-only)\fR"
/*        The master.cf service name of a Postfix daemon process.
/* .PP
/*        Available in Postfix 3.7 and later:
/* .IP "\fBsmtp_bind_address_enforce (no)\fR"
/*        Defer delivery when the Postfix SMTP client cannot apply the
/*        smtp_bind_address or smtp_bind_address6 setting.
/* SEE ALSO
/*        generic(5), output address rewriting
/*        header_checks(5), message header content inspection
/*        body_checks(5), body parts content inspection
/*        qmgr(8), queue manager
/*        bounce(8), delivery status reports
/*        scache(8), connection cache server
/*        postconf(5), configuration parameters
/*        master(5), generic daemon options
/*        master(8), process manager
/*        tlsmgr(8), TLS session and PRNG management
/*        postlogd(8), Postfix logging
/*        syslogd(8), system logging
/* README FILES
/* .ad
/* .fi
/*        Use "\fBpostconf readme_directory\fR" or
/*        "\fBpostconf html_directory\fR" to locate this information.
/* .na
/* .nf
/*        SASL_README, Postfix SASL howto
/*        TLS_README, Postfix STARTTLS howto
/* LICENSE
/* .ad
/* .fi
/*        The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*        Wietse Venema
/*        IBM T.J. Watson Research
/*        P.O. Box 704
/*        Yorktown Heights, NY 10598, USA
/*
/*        Wietse Venema
/*        Google, Inc.
/*        111 8th Avenue
/*        New York, NY 10011, USA
/*
/*        Command pipelining in cooperation with:
/*        Jon Ribbens
/*        Oaktree Internet Solutions Ltd.,
/*        Internet House,
/*        Canal Basin,
/*        Coventry,
/*        CV1 4LY, United Kingdom.
/*
/*        SASL support originally by:
/*        Till Franke
/*        SuSE Rhein/Main AG
/*        65760 Eschborn, Germany
/*
/*        TLS support originally by:
/*        Lutz Jaenicke
/*        BTU Cottbus
/*        Allgemeine Elektrotechnik
/*        Universitaetsplatz 3-4
/*        D-03044 Cottbus, Germany
/*
/*        Revised TLS and SMTP connection cache support by:
/*        Victor Duchovni
/*        Morgan Stanley
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <dict.h>
#include <stringops.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <name_mask.h>
#include <name_code.h>
#include <byte_mask.h>

/* Global library. */

#include <deliver_request.h>
#include <delivered_hdr.h>
#include <mail_proto.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_conf.h>
#include <debug_peer.h>
#include <flush_clnt.h>
#include <scache.h>
#include <string_list.h>
#include <maps.h>
#include <ext_prop.h>
#include <hfrom_format.h>

/* DNS library. */

#include <dns.h>

/* Single server skeleton. */

#include <mail_server.h>

/* Application-specific. */

#include "smtp.h"
#include "smtp_sasl.h"

 /*
  * Tunable parameters. These have compiled-in defaults that can be overruled
  * by settings in the global Postfix configuration file.
  */
int     var_smtp_conn_tmout;
int     var_smtp_helo_tmout;
int     var_smtp_xfwd_tmout;
int     var_smtp_mail_tmout;
int     var_smtp_rcpt_tmout;
int     var_smtp_data0_tmout;
int     var_smtp_data1_tmout;
int     var_smtp_data2_tmout;
int     var_smtp_rset_tmout;
int     var_smtp_quit_tmout;
char   *var_notify_classes;
int     var_smtp_skip_5xx_greeting;
int     var_ign_mx_lookup_err;
int     var_skip_quit_resp;
char   *var_fallback_relay;
char   *var_bestmx_transp;
char   *var_error_rcpt;
int     var_smtp_always_ehlo;
int     var_smtp_never_ehlo;
char   *var_smtp_sasl_opts;
char   *var_smtp_sasl_path;
char   *var_smtp_sasl_passwd;
char   *var_smtp_sasl_passwd_res_delim;
bool    var_smtp_sasl_enable;
char   *var_smtp_sasl_mechs;
char   *var_smtp_sasl_type;
char   *var_smtp_bind_addr;
char   *var_smtp_bind_addr6;
char   *var_smtp_vrfy_tgt;
bool    var_smtp_rand_addr;
int     var_smtp_pix_thresh;
int     var_queue_run_delay;
int     var_min_backoff_time;
int     var_smtp_pix_delay;
int     var_smtp_line_limit;
char   *var_smtp_helo_name;
char   *var_smtp_host_lookup;
bool    var_smtp_quote_821_env;
bool    var_smtp_defer_mxaddr;
bool    var_smtp_send_xforward;
int     var_smtp_mxaddr_limit;
int     var_smtp_mxsess_limit;
int     var_smtp_cache_conn;
int     var_smtp_reuse_time;
int     var_smtp_reuse_count;
char   *var_smtp_cache_dest;
char   *var_scache_service;             /* You can now leave this here. */
bool    var_smtp_cache_demand;
char   *var_smtp_ehlo_dis_words;
char   *var_smtp_ehlo_dis_maps;
char   *var_smtp_addr_pref;

char   *var_smtp_tls_level;
bool    var_smtp_use_tls;
bool    var_smtp_enforce_tls;
char   *var_smtp_tls_per_site;
char   *var_smtp_tls_policy;
bool    var_smtp_tls_wrappermode;
bool    var_smtp_tls_conn_reuse;
char   *var_tlsproxy_service;

#ifdef USE_TLS
char   *var_smtp_sasl_tls_opts;
char   *var_smtp_sasl_tlsv_opts;
int     var_smtp_starttls_tmout;
char   *var_smtp_tls_CAfile;
char   *var_smtp_tls_CApath;
char   *var_smtp_tls_chain_files;
char   *var_smtp_tls_cert_file;
char   *var_smtp_tls_mand_ciph;
char   *var_smtp_tls_excl_ciph;
char   *var_smtp_tls_mand_excl;
char   *var_smtp_tls_dcert_file;
char   *var_smtp_tls_dkey_file;
bool    var_smtp_tls_enforce_peername;
char   *var_smtp_tls_key_file;
char   *var_smtp_tls_loglevel;
bool    var_smtp_tls_note_starttls_offer;
char   *var_smtp_tls_mand_proto;
char   *var_smtp_tls_sec_cmatch;
int     var_smtp_tls_scert_vd;
char   *var_smtp_tls_vfy_cmatch;
char   *var_smtp_tls_fpt_cmatch;
char   *var_smtp_tls_fpt_dgst;
char   *var_smtp_tls_tafile;
char   *var_smtp_tls_proto;
char   *var_smtp_tls_ciph;
char   *var_smtp_tls_eccert_file;
char   *var_smtp_tls_eckey_file;
char   *var_smtp_tls_sni;
bool    var_smtp_tls_blk_early_mail_reply;
bool    var_smtp_tls_force_tlsa;
char   *var_smtp_tls_insecure_mx_policy;
bool    var_smtp_tls_enable_rpk;

#endif

char   *var_smtp_generic_maps;
char   *var_prop_extension;
bool    var_smtp_sender_auth;
char   *var_smtp_tcp_port;
int     var_scache_proto_tmout;
bool    var_smtp_cname_overr;
char   *var_smtp_pix_bug_words;
char   *var_smtp_pix_bug_maps;
char   *var_cyrus_conf_path;
char   *var_smtp_head_chks;
char   *var_smtp_mime_chks;
char   *var_smtp_nest_chks;
char   *var_smtp_body_chks;
char   *var_smtp_resp_filter;
bool    var_lmtp_assume_final;
char   *var_smtp_dns_res_opt;
char   *var_smtp_dns_support;
bool    var_smtp_dummy_mail_auth;
char   *var_smtp_dsn_filter;
char   *var_smtp_dns_re_filter;
bool    var_smtp_balance_inet_proto;
bool    var_smtp_req_deadline;
int     var_smtp_min_data_rate;
char   *var_use_srv_lookup;
bool    var_ign_srv_lookup_err;
bool    var_allow_srv_fallback;
bool    var_smtp_tlsrpt_enable;
char   *var_smtp_tlsrpt_sockname;
bool    var_smtp_tlsrpt_skip_reused_hs;

 /* Special handling of 535 AUTH errors. */
char   *var_smtp_sasl_auth_cache_name;
int     var_smtp_sasl_auth_cache_time;
bool    var_smtp_sasl_auth_soft_bounce;

char   *var_hfrom_format;
bool    var_smtp_bind_addr_enforce;

 /*
  * Global variables.
  */
int     smtp_mode;
int     smtp_host_lookup_mask;
int     smtp_dns_support;
STRING_LIST *smtp_cache_dest;
SCACHE *smtp_scache;
MAPS   *smtp_ehlo_dis_maps;
MAPS   *smtp_generic_maps;
int     smtp_ext_prop_mask;
unsigned smtp_dns_res_opt;
MAPS   *smtp_pix_bug_maps;
HBC_CHECKS *smtp_header_checks;                   /* limited header checks */
HBC_CHECKS *smtp_body_checks;           /* limited body checks */
SMTP_CLI_ATTR smtp_cli_attr;            /* parsed command-line */
int     smtp_hfrom_format;              /* postmaster notifications */
STRING_LIST *smtp_use_srv_lookup;

#ifdef USE_TLS

 /*
  * OpenSSL client state (opaque handle)
  */
TLS_APPL_STATE *smtp_tls_ctx;
int     smtp_tls_insecure_mx_policy;

#endif

 /*
  * IPv6 preference.
  */
static int smtp_addr_pref;

/* get_cli_attr - get command-line attributes */

static void get_cli_attr(SMTP_CLI_ATTR *attr, char **argv)
{
    const char myname[] = "get_cli_attr";
    const char *last_flags = "flags=";  /* i.e. empty */
    static const BYTE_MASK flags_map[] = {
          'D', SMTP_CLI_FLAG_DELIVERED_TO,
          'O', SMTP_CLI_FLAG_ORIG_RCPT,
          'R', SMTP_CLI_FLAG_RETURN_PATH,
          'X', SMTP_CLI_FLAG_FINAL_DELIVERY,
          0,
    };

    /*
     * Initialize.
     */
    attr->flags = 0;

    /*
     * Iterate over the command-line attribute list. Errors are fatal.
     */
    for ( /* void */ ; *argv != 0; argv++) {

          /*
           * flags=stuff. Errors are fatal.
           */
          if (strncasecmp("flags=", *argv, sizeof("flags=") - 1) == 0) {
              last_flags = *argv;
              if (msg_verbose)
                    msg_info("%s: %s", myname, last_flags);
              attr->flags = byte_mask(*argv, flags_map,
                                            *argv + sizeof("flags=") - 1);
          }

          /*
           * Bad.
           */
          else
              msg_fatal("unknown attribute name: %s", *argv);
    }

    /*
     * Backwards compatibility, redundancy, and obsolescence.
     */
    if (!smtp_mode && var_lmtp_assume_final
          && (attr->flags & SMTP_CLI_FLAG_FINAL_DELIVERY) == 0) {
          attr->flags |= SMTP_CLI_FLAG_FINAL_DELIVERY;
          msg_warn("%s is obsolete; instead, specify \"%sX\" in %s",
                     VAR_LMTP_ASSUME_FINAL, last_flags, MASTER_CONF_FILE);
    }
}

/* deliver_message - deliver message with extreme prejudice */

static int deliver_message(const char *service, DELIVER_REQUEST *request)
{
    SMTP_STATE *state;
    int     result;

    if (msg_verbose)
          msg_info("deliver_message: from %s", request->sender);

    /*
     * Sanity checks. The smtp server is unprivileged and chrooted, so we can
     * afford to distribute the data censoring code, instead of having it all
     * in one place.
     */
    if (request->nexthop[0] == 0)
          msg_fatal("empty nexthop hostname");
    if (request->rcpt_list.len <= 0)
          msg_fatal("recipient count: %d", request->rcpt_list.len);

    /*
     * D flag checks.
     */
    if (smtp_cli_attr.flags & SMTP_CLI_FLAG_DELIVERED_TO) {

          /*
           * The D flag cannot be specified for multi-recipient deliveries.
           */
          if (request->rcpt_list.len > 1) {
              msg_warn("flag `D' requires %s_destination_recipient_limit = 1",
                         service);
              return (reject_deliver_request(service, request, "4.3.5",
                                                  "mail system configuration error"));
          }

          /*
           * The recipient cannot appear in a Delivered-To: header.
           */
          else {
              DELIVERED_HDR_INFO *delivered_info = delivered_hdr_init(
                                request->fp, request->data_offset, FOLD_ADDR_ALL);
              VSTRING *generic_rcpt = vstring_alloc(100);
              int     have_delivered_loop;

              smtp_rewrite_generic_internal(generic_rcpt,
                                                    request->rcpt_list.info->address);
              have_delivered_loop = delivered_hdr_find(
                                                   delivered_info, STR(generic_rcpt));
              vstring_free(generic_rcpt);
              delivered_hdr_free(delivered_info);
              if (have_delivered_loop) {
                    return (reject_deliver_request(service, request, "5.4.6",
                                                         "mail forwarding loop for %s",
                                                   request->rcpt_list.info->address));
              }
          }
    }

    /*
     * The O flag cannot be specified for multi-recipient deliveries.
     */
    if ((smtp_cli_attr.flags & SMTP_CLI_FLAG_ORIG_RCPT)
          && request->rcpt_list.len > 1) {
          msg_warn("flag `O' requires %s_destination_recipient_limit = 1",
                     service);
          return (reject_deliver_request(service, request, "4.3.5",
                                               "mail system configuration error"));
    }

    /*
     * Initialize. Bundle all information about the delivery request, so that
     * we can produce understandable diagnostics when something goes wrong
     * many levels below. The alternative would be to make everything global.
     */
    state = smtp_state_alloc();
    state->request = request;
    state->src = request->fp;
    state->service = service;
    state->misc_flags |= smtp_addr_pref;
    state->debug_peer_per_nexthop =
          debug_peer_check(request->nexthop, "noaddr");
    SMTP_RCPT_INIT(state);

    /*
     * Establish an SMTP session and deliver this message to all requested
     * recipients. At the end, notify the postmaster of any protocol errors.
     * Optionally deliver mail locally when this machine is the best mail
     * exchanger.
     */
    result = smtp_connect(state);

    /*
     * Clean up.
     */
    smtp_state_free(state);

    return (result);
}

/* smtp_service - perform service for client */

static void smtp_service(VSTREAM *client_stream, char *service,
                                       char **unused_argv)
{
    DELIVER_REQUEST *request;
    int     status;

    /*
     * This routine runs whenever a client connects to the UNIX-domain socket
     * dedicated to remote SMTP delivery service. What we see below is a
     * little protocol to (1) tell the queue manager that we are ready, (2)
     * read a request from the queue manager, and (3) report the completion
     * status of that request. All connection-management stuff is handled by
     * the common code in single_server.c.
     */
    if ((request = deliver_request_read(client_stream)) != 0) {
          status = deliver_message(service, request);
          deliver_request_done(client_stream, request, status);
    }
}

/* post_init - post-jail initialization */

static void post_init(char *unused_name, char **argv)
{
    static const NAME_MASK lookup_masks[] = {
          SMTP_HOST_LOOKUP_DNS, SMTP_HOST_FLAG_DNS,
          SMTP_HOST_LOOKUP_NATIVE, SMTP_HOST_FLAG_NATIVE,
          0,
    };
    static const NAME_MASK dns_res_opt_masks[] = {
          SMTP_DNS_RES_OPT_DEFNAMES, RES_DEFNAMES,
          SMTP_DNS_RES_OPT_DNSRCH, RES_DNSRCH,
          0,
    };
    static const NAME_CODE dns_support[] = {
          SMTP_DNS_SUPPORT_DISABLED, SMTP_DNS_DISABLED,
          SMTP_DNS_SUPPORT_ENABLED, SMTP_DNS_ENABLED,
#if (RES_USE_DNSSEC != 0) && (RES_USE_EDNS0 != 0)
          SMTP_DNS_SUPPORT_DNSSEC, SMTP_DNS_DNSSEC,
#endif
          0, SMTP_DNS_INVALID,
    };

    if (*var_smtp_dns_support == 0) {
          /* Backwards compatible empty setting */
          smtp_dns_support =
              var_disable_dns ? SMTP_DNS_DISABLED : SMTP_DNS_ENABLED;
    } else {
          smtp_dns_support =
              name_code(dns_support, NAME_CODE_FLAG_NONE, var_smtp_dns_support);
          if (smtp_dns_support == SMTP_DNS_INVALID)
              msg_fatal("invalid %s: \"%s\"", VAR_LMTP_SMTP(DNS_SUPPORT),
                          var_smtp_dns_support);
          var_disable_dns = (smtp_dns_support == SMTP_DNS_DISABLED);
    }

#if !defined(USE_TLS) || !defined(USE_TLSRPT)
    if (var_smtp_tlsrpt_enable)
          msg_warn("TLSRPT is selected, but TLSRPT is not compiled in");
#endif
#ifdef USE_TLS
#ifdef USE_TLSRPT
    if (var_smtp_tlsrpt_enable) {
          if (smtp_mode) {
              if (smtp_tlsrpt_post_jail(VAR_SMTP_TLSRPT_SOCKNAME,
                                              var_smtp_tlsrpt_sockname) < 0)
                    var_smtp_tlsrpt_enable = 0;
          } else {
              msg_warn("TLSRPT support is not implemented for LMTP");
              var_smtp_tlsrpt_enable = 0;
          }
    }
#endif                                                      /* USE_TLSRPT */
    if (smtp_mode) {
          smtp_tls_insecure_mx_policy =
              tls_level_lookup(var_smtp_tls_insecure_mx_policy);
          switch (smtp_tls_insecure_mx_policy) {
          case TLS_LEV_MAY:
          case TLS_LEV_ENCRYPT:
          case TLS_LEV_DANE:
              break;
          default:
              msg_fatal("invalid %s: \"%s\"", VAR_SMTP_TLS_INSECURE_MX_POLICY,
                          var_smtp_tls_insecure_mx_policy);
          }
    }
#endif

    /*
     * Select hostname lookup mechanisms.
     */
    if (smtp_dns_support == SMTP_DNS_DISABLED)
          smtp_host_lookup_mask = SMTP_HOST_FLAG_NATIVE;
    else
          smtp_host_lookup_mask =
              name_mask(VAR_LMTP_SMTP(HOST_LOOKUP), lookup_masks,
                          var_smtp_host_lookup);
    if (msg_verbose)
          msg_info("host name lookup methods: %s",
                     str_name_mask(VAR_LMTP_SMTP(HOST_LOOKUP), lookup_masks,
                                     smtp_host_lookup_mask));

    /*
     * Session cache instance.
     */
    if (*var_smtp_cache_dest || var_smtp_cache_demand)
#if 0
          smtp_scache = scache_multi_create();
#else
          smtp_scache = scache_clnt_create(var_scache_service,
                                                   var_scache_proto_tmout,
                                                   var_ipc_idle_limit,
                                                   var_ipc_ttl_limit);
#endif

    /*
     * Select DNS query flags.
     */
    smtp_dns_res_opt = name_mask(VAR_LMTP_SMTP(DNS_RES_OPT), dns_res_opt_masks,
                                         var_smtp_dns_res_opt);

    /*
     * Address verification.
     */
    smtp_vrfy_init();

    /*
     * Look up service command-line attributes; these do not change during
     * the process lifetime.
     */
    get_cli_attr(&smtp_cli_attr, argv);

    /*
     * header_from format, for postmaster notifications.
     */
    smtp_hfrom_format = hfrom_format_parse(VAR_HFROM_FORMAT, var_hfrom_format);

    /*
     * Service discovery with SRV record lookup.
     */
    if (*var_use_srv_lookup)
          smtp_use_srv_lookup = string_list_init(VAR_USE_SRV_LOOKUP,
                                                         MATCH_FLAG_RETURN,
                                                         var_use_srv_lookup);
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{
    int     use_tls;
    static const NAME_CODE addr_pref_map[] = {
          INET_PROTO_NAME_IPV6, SMTP_MISC_FLAG_PREF_IPV6,
          INET_PROTO_NAME_IPV4, SMTP_MISC_FLAG_PREF_IPV4,
          INET_PROTO_NAME_ANY, 0,
          0, -1,
    };

    /*
     * The process name, "smtp" or "lmtp", determines the configuration
     * parameters to use, protocol, DSN server reply type, SASL service
     * information lookup, and more. We peeked at the name in the main()
     * function before logging was initialized. Here, we detect and report an
     * invalid process name.
     */
    if (strcmp(var_procname, MAIL_PROC_NAME_SMTP) != 0
          && strcmp(var_procname, MAIL_PROC_NAME_LMTP) != 0)
          msg_fatal("unexpected process name \"%s\" - "
                      "specify \"%s\" or \"%s\"", var_procname,
                      MAIL_PROC_NAME_SMTP, MAIL_PROC_NAME_LMTP);

    /*
     * Turn on per-peer debugging.
     */
    debug_peer_init();

    /*
     * SASL initialization.
     */
    if (var_smtp_sasl_enable)
#ifdef USE_SASL_AUTH
          smtp_sasl_initialize();
#else
          msg_warn("%s is true, but SASL support is not compiled in",
                     VAR_LMTP_SMTP(SASL_ENABLE));
#endif

    if (*var_smtp_tls_level != 0)
#ifdef USE_TLS
          switch (tls_level_lookup(var_smtp_tls_level)) {
          case TLS_LEV_SECURE:
          case TLS_LEV_VERIFY:
          case TLS_LEV_DANE_ONLY:
          case TLS_LEV_FPRINT:
          case TLS_LEV_ENCRYPT:
              var_smtp_use_tls = var_smtp_enforce_tls = 1;
              break;
          case TLS_LEV_DANE:
          case TLS_LEV_MAY:
              var_smtp_use_tls = 1;
              var_smtp_enforce_tls = 0;
              break;
          case TLS_LEV_NONE:
              var_smtp_use_tls = var_smtp_enforce_tls = 0;
              break;
          default:
              /* tls_level_lookup() logs no warning. */
              /* session_tls_init() assumes that var_smtp_tls_level is sane. */
              msg_fatal("Invalid TLS level \"%s\"", var_smtp_tls_level);
          }
#endif
    use_tls = (var_smtp_use_tls || var_smtp_enforce_tls);

    /*
     * Initialize the TLS data before entering the chroot jail
     */
    if (use_tls || var_smtp_tls_per_site[0] || var_smtp_tls_policy[0]) {
#ifdef USE_TLS
          TLS_CLIENT_INIT_PROPS props;

          tls_pre_jail_init(TLS_ROLE_CLIENT);

          /*
           * We get stronger type safety and a cleaner interface by combining
           * the various parameters into a single tls_client_props structure.
           *
           * Large parameter lists are error-prone, so we emulate a language
           * feature that C does not have natively: named parameter lists.
           *
           * With tlsproxy(8) turned on, this is still needed for DANE-related
           * initializations.
           */
          smtp_tls_ctx =
              TLS_CLIENT_INIT(&props,
                                  log_param = VAR_LMTP_SMTP(TLS_LOGLEVEL),
                                  log_level = var_smtp_tls_loglevel,
                                  verifydepth = var_smtp_tls_scert_vd,
                                  cache_type = LMTP_SMTP_SUFFIX(TLS_MGR_SCACHE),
                                  chain_files = var_smtp_tls_chain_files,
                                  cert_file = var_smtp_tls_cert_file,
                                  key_file = var_smtp_tls_key_file,
                                  dcert_file = var_smtp_tls_dcert_file,
                                  dkey_file = var_smtp_tls_dkey_file,
                                  eccert_file = var_smtp_tls_eccert_file,
                                  eckey_file = var_smtp_tls_eckey_file,
                                  CAfile = var_smtp_tls_CAfile,
                                  CApath = var_smtp_tls_CApath,
                                  mdalg = var_smtp_tls_fpt_dgst);
          smtp_tls_list_init();
          tls_dane_loglevel(VAR_LMTP_SMTP(TLS_LOGLEVEL), var_smtp_tls_loglevel);
#else
          msg_warn("TLS has been selected, but TLS support is not compiled in");
#endif
    }

    /*
     * Flush client.
     */
    flush_init();

    /*
     * Session cache domain list.
     */
    if (*var_smtp_cache_dest)
          smtp_cache_dest = string_list_init(VAR_SMTP_CACHE_DEST,
                                                     MATCH_FLAG_RETURN,
                                                     var_smtp_cache_dest);

    /*
     * EHLO keyword filter.
     */
    if (*var_smtp_ehlo_dis_maps)
          smtp_ehlo_dis_maps = maps_create(VAR_LMTP_SMTP(EHLO_DIS_MAPS),
                                                   var_smtp_ehlo_dis_maps,
                                                   DICT_FLAG_LOCK);

    /*
     * PIX bug workarounds.
     */
    if (*var_smtp_pix_bug_maps)
          smtp_pix_bug_maps = maps_create(VAR_LMTP_SMTP(PIX_BUG_MAPS),
                                                  var_smtp_pix_bug_maps,
                                                  DICT_FLAG_LOCK);

    /*
     * Generic maps.
     */
    if (*var_prop_extension)
          smtp_ext_prop_mask =
              ext_prop_mask(VAR_PROP_EXTENSION, var_prop_extension);
    if (*var_smtp_generic_maps)
          smtp_generic_maps =
              maps_create(VAR_LMTP_SMTP(GENERIC_MAPS), var_smtp_generic_maps,
                              DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX
                              | DICT_FLAG_UTF8_REQUEST);

    /*
     * Header/body checks.
     */
    smtp_header_checks = hbc_header_checks_create(
                                     VAR_LMTP_SMTP(HEAD_CHKS), var_smtp_head_chks,
                                     VAR_LMTP_SMTP(MIME_CHKS), var_smtp_mime_chks,
                                     VAR_LMTP_SMTP(NEST_CHKS), var_smtp_nest_chks,
                                                              smtp_hbc_callbacks);
    smtp_body_checks = hbc_body_checks_create(
                                     VAR_LMTP_SMTP(BODY_CHKS), var_smtp_body_chks,
                                                        smtp_hbc_callbacks);

    /*
     * Server reply filter.
     */
    if (*var_smtp_resp_filter)
          smtp_chat_resp_filter =
              dict_open(var_smtp_resp_filter, O_RDONLY,
                          DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX);

    /*
     * Address family preference.
     */
    if (*var_smtp_addr_pref) {
          smtp_addr_pref = name_code(addr_pref_map, NAME_CODE_FLAG_NONE,
                                           var_smtp_addr_pref);
          if (smtp_addr_pref < 0)
              msg_fatal("bad %s value: %s", VAR_LMTP_SMTP(ADDR_PREF),
                          var_smtp_addr_pref);
    }

    /*
     * DNS reply filter.
     */
    if (*var_smtp_dns_re_filter)
          dns_rr_filter_compile(VAR_LMTP_SMTP(DNS_RE_FILTER),
                                    var_smtp_dns_re_filter);
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if ((table = dict_changed_name()) != 0) {
          msg_info("table %s has changed -- restarting", table);
          exit(0);
    }
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the single-threaded skeleton */

int     main(int argc, char **argv)
{
    char   *sane_procname;

#include "smtp_params.c"
#include "lmtp_params.c"

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    /*
     * XXX The process name, "smtp" or "lmtp", determines what configuration
     * parameter settings to use, and more. However, at this point, logging
     * and var_procname are not initialized. Here, we peek at the process
     * name to determine what configuration parameter settings to use. Later,
     * we detect and report an invalid process name.
     */
    sane_procname = sane_basename((VSTRING *) 0, argv[0]);
    if (strcmp(sane_procname, MAIL_PROC_NAME_SMTP) == 0)
          smtp_mode = 1;

    /*
     * Initialize with the LMTP or SMTP parameter name space.
     */
    single_server_main(argc, argv, smtp_service,
                           CA_MAIL_SERVER_TIME_TABLE(smtp_mode ?
                                                   smtp_time_table : lmtp_time_table),
                           CA_MAIL_SERVER_INT_TABLE(smtp_mode ?
                                                     smtp_int_table : lmtp_int_table),
                           CA_MAIL_SERVER_STR_TABLE(smtp_mode ?
                                                     smtp_str_table : lmtp_str_table),
                           CA_MAIL_SERVER_BOOL_TABLE(smtp_mode ?
                                                   smtp_bool_table : lmtp_bool_table),
                           CA_MAIL_SERVER_NBOOL_TABLE(smtp_mode ?
                                               smtp_nbool_table : lmtp_nbool_table),
                           CA_MAIL_SERVER_PRE_INIT(pre_init),
                           CA_MAIL_SERVER_POST_INIT(post_init),
                           CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
                           CA_MAIL_SERVER_BOUNCE_INIT(VAR_SMTP_DSN_FILTER,
                                                              &var_smtp_dsn_filter),
                           0);
}