This is msmtp.info, produced by makeinfo version 5.2 from msmtp.texi.

This manual was last updated 8 March 2014 for version 1.4.32 of msmtp.

   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
2014 Martin Lambers
Copyright (C) 2011 Scott Shumate

     Copying and distribution of this file, with or without
     modification, are permitted in any medium without royalty provided
     the copyright notice and this notice are preserved.  These files
     are offered as-is, without any warranty.
INFO-DIR-SECTION Individual utilities
START-INFO-DIR-ENTRY
* msmtp: (msmtp).	An SMTP client.
END-INFO-DIR-ENTRY


File: msmtp.info,  Node: Top,  Next: Introduction,  Up: (dir)

msmtp
*****

This manual was last updated 8 March 2014 for version 1.4.32 of msmtp.

   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
2014 Martin Lambers
Copyright (C) 2011 Scott Shumate

     Copying and distribution of this file, with or without
     modification, are permitted in any medium without royalty provided
     the copyright notice and this notice are preserved.  These files
     are offered as-is, without any warranty.

* Menu:

* Introduction::			Basic concepts.
* Configuration files::			Configuration file commands.
* Invocation::				Command line options.
* Transport Layer Security::		How to use TLS/SSL.
* Authentication::			How to use authentication.
* Delivery Status Notifications::	How to use DSN.
* Sendmail mode::			How to send mail.
* Server information mode::		How to obtain information about
					an SMTP server.
* Remote Message Queue Starting mode::	How to send RMQS requests.
* Examples::				Usage examples.


File: msmtp.info,  Node: Introduction,  Next: Configuration files,  Prev: Top,  Up: Top

1 Introduction
**************

msmtp is an SMTP client.

   In its default mode of operation, it reads a mail from standard input
and sends it to a predefined SMTP server that takes care of proper
delivery.  Command line options and exit codes are compatible to
sendmail.

   Supported SMTP features include:
   • Authentication methods PLAIN, LOGIN, CRAM-MD5 and EXTERNAL (and
     GSSAPI, SCRAM-SHA-1, DIGEST-MD5, and NTLM when compiled with GNU
     SASL support)
   • TLS encrypted connections with the OpenSSL or GnuTLS libraries
     (including server certificate verification and the possibility to
     send a client certificate)
   • Support for Internationalized Domain Names (IDN)
   • DSN (Delivery Status Notification) support
   • PIPELINING support for increased transmission speed
   • RMQS (Remote Message Queue Starting) support (ETRN keyword)

   The best way to start is probably to have a look at the Examples
section.  *Note Examples::.

   In addition to sendmail mode, there are two other modes of operation:
   • Server information mode.  In this mode, msmtp prints as much
     information as it can get about a given SMTP server (supported
     features, maximum mail size, …).
   • Remote Message Queue Starting mode.  In this mode, msmtp sends a
     Remote Message Queue Starting request for a host, domain, or queue
     to a given SMTP server.

   Normally, a system wide configuration file and/or a user
configuration file contain information about which SMTP server to use
and how to use it, but almost all settings can also be configured on the
command line.

   The information about SMTP servers is organized in accounts.  Each
account describes one SMTP server: host name, authentication settings,
TLS settings, and so on.  Each configuration file can define multiple
accounts.


File: msmtp.info,  Node: Configuration files,  Next: Invocation,  Prev: Introduction,  Up: Top

2 Configuration files
*********************

msmtp supports a system wide configuration file and a user configuration
file.  Both are optional and need not exist.

   If it exists and is readable, a system wide configuration file
‘SYSCONFDIR/msmtprc’ will be loaded, where ‘SYSCONFDIR’ depends on your
platform.  The default is ‘/usr/local/etc’.  Use ‘--version’ to find out
which directory your version uses.

   If it exists and is readable, a user configuration file will be
loaded (‘~/.msmtprc’ by default).  Accounts defined in the user
configuration file override accounts from the system configuration file.
The user configuration file must have no more permissions than user
read/write.  Configuration data from either file can be changed by
command line options.

   A configuration file is a simple text file.  Empty lines and comment
lines (whose first non-blank character is ’#’) are ignored.  Every other
line must contain a command and may contain an argument to that command.
The argument may be enclosed in double quotes (").

   If the first character of a filename is the tilde (~), this tilde
will be replaced by ‘HOME’.  If a command accepts the argument ‘on’, it
also accepts an empty argument and treats that as if it was ‘on’.

   Commands form groups.  Each group starts with the ‘account’ command
and defines the settings for one SMTP server.

   *Note Examples::.

2.1 General commands
====================

‘defaults’
     Set defaults.  The following configuration commands will set
     default values for all following account definitions in the current
     configuration file.
‘account NAME [: ACCOUNT[,…]]’
     Start a new account definition with the given name.  The current
     default values are filled in (see *note defaults::).
     If a colon and a list of previously defined accounts is given after
     the account name, the new account, with the filled in default
     values, will inherit all settings from the accounts in the list.
‘host HOSTNAME’
     The SMTP server to send the mail to.  The argument may be a host
     name or a network address.  Every account definition must contain
     this command.
‘port NUMBER’
     The port that the SMTP server listens on.  The default port will be
     acquired from your operating system’s service database: for SMTP,
     the service is "smtp" (default port 25), unless TLS without
     STARTTLS is used, in which case it is "smtps" (465).  For LMTP, it
     is "lmtp".
‘timeout (off|SECONDS)’
     Set or unset a network timeout, in seconds.  The argument ‘off’
     means that no timeout will be set, which means that the operating
     system default will be used.  For compatibility with older
     versions, ‘connect_timeout’ is accepted as an alias for this
     command.
‘protocol (smtp|lmtp)’
     Set the protocol to use.  Currently only SMTP and LMTP are
     supported.  SMTP is the default.  See *note port:: for default
     ports.
‘domain ARGUMENT’
     This command sets the argument of the SMTP EHLO (or LMTP LHLO)
     command.  The default is ‘localhost’, which is stupid but usually
     works.  Try to change the default if mails get rejected due to
     anti-SPAM measures.  Possible choices are the domain part of your
     mail address (‘provider.example’ for ‘joe@provider.example’) or the
     fully qualified domain name of your host (if available).

2.2 Authentication commands
===========================

*Note Authentication::.

‘auth [(on|off|METHOD)]’
     This command enables or disables SMTP authentication and optionally
     chooses an authentication method to use.  It should not be
     necessary to choose a method; with the argument ‘on’, msmtp will
     choose the best one available.  Accepted methods are ‘plain’,
     ‘scram-sha-1’, ‘cram-md5’, ‘gssapi’, ‘external’, ‘digest-md5’,
     ‘login’, and ‘ntlm’.  *Note Authentication::.
‘user [USERNAME]’
     Set your user name for SMTP authentication.  An empty argument
     unsets the user name.  Authentication must be activated with the
     ‘auth’ command.
‘password [SECRET]’
     Set your password for SMTP authentication.  An empty argument
     unsets the password.  Authentication must be activated with the
     ‘auth’ command.  If no password is set but one is needed during
     authentication, msmtp will try to find it.  First, if
     ‘passwordeval’ is set, it will evaluate that command.  If
     ‘passwordeval’ is not set, msmtp will try to find the password in
     ‘~/.netrc’.  If that fails, it will try to find it in
     ‘SYSCONFDIR/netrc’ (use ‘--version’ to find out what ‘SYSCONFDIR’
     is on your platform).  If that fails, it will try to get it from a
     system specific keyring (if available).  If that fails but a
     controlling terminal is available, msmtp will prompt you for it.
     *Note Authentication::.
‘passwordeval [EVAL]’
     Set your password for SMTP authentication to the output (stdout) of
     the execution of EVAL.
‘ntlmdomain [NTLMDOMAIN]’
     Set a domain for the ‘ntlm’ authentication method.  The default is
     to use no domain (equivalent to an empty argument), but some
     servers seem to require one, even if it is an arbitrary string.

2.3 TLS commands
================

*Note Transport Layer Security::.

‘tls [(on|off)]’
     This command enables or disables TLS/SSL encrypted connections to
     the SMTP server.  Not every server supports TLS, and a few that
     support it require the ‘tls_starttls off’ command.
     To use TLS/SSL, it is required to either use the ‘tls_trust_file’
     command (highly recommended) or to disable ‘tls_certcheck’.  *Note
     Transport Layer Security::.
‘tls_trust_file [FILE]’
     This command activates strict server certificate verification.  The
     given file must contain one or more certificates of trusted
     Certification Authorities (CAs) in PEM format.
     On Debian based systems, you can install the ‘ca-certificates’
     package and use the file ‘/etc/ssl/certs/ca-certificates.crt’.
     An empty argument disables this feature.
‘tls_crl_file [FILE]’
     This command sets or unsets a certificate revocation list (CRL)
     file for TLS, to be used during strict server certificate
     verification as enabled by the *note tls_trust_file:: command.
     This allows the verification procedure to detect revoked
     certificates.  *Note Transport Layer Security::.
‘tls_fingerprint [FINGERPRINT]’
     This command sets or unsets the fingerprint of a particular TLS
     certificate.  This certificate will then be trusted, regardless of
     its contents.  This can be used to trust broken certificates (e.g.
     with a non-matching hostname) or in situations where
     ‘tls_trust_file’ cannot be used for some reason.  You can give
     either an SHA1 (recommended) or an MD5 fingerprint in the format
     ‘01:23:45:67:…’.  You can use ‘--serverinfo --tls
     --tls-certcheck=off’ to get the peer certificate’s fingerprints.
     *Note Transport Layer Security::.
‘tls_key_file [FILE]’
     This command (together with the ‘tls_cert_file’) command enables
     msmtp to send a client certificate to the SMTP server if requested.
     The file must contain the private key of a certificate in PEM
     format.  An empty argument disables this feature.  *Note Transport
     Layer Security::.
‘tls_cert_file [FILE]’
     This command (together with the ‘tls_key_file’ command) enables
     msmtp to send a client certificate to the SMTP server if requested.
     The file must contain a certificate in PEM format.  An empty
     argument disables this feature.  *Note Transport Layer Security::.
‘tls_certcheck [(on|off)]’
     This command enables or disables checks for the server certificate.
     WARNING: When the checks are disabled, TLS/SSL sessions will be
     vulnerable to man-in-the-middle attacks!  *Note Transport Layer
     Security::.
     For compatibility with older versions, ‘tls_nocertcheck’ is
     accepted as an alias for ‘tls_certcheck off’.
‘tls_starttls [(on|off)]’
     This command enables or disables the use of the STARTTLS SMTP
     command to start TLS encryption.  It is enabled by default.  *Note
     Transport Layer Security::.  For compatibility with older versions,
     ‘tls_nostarttls’ is accepted as an alias for ‘tls_starttls off’.
‘tls_force_sslv3 [(on|off)]’
     Force TLS/SSL version SSLv3.  This might be needed to use SSL with
     some old and broken servers.  Do not use this unless you have to.
     *Note Transport Layer Security::.
‘tls_min_dh_prime_bits [BITS]’
     Set or unset the minimum number of Diffie-Hellman (DH) prime bits
     that msmtp will accept for TLS sessions.  The default is set by the
     TLS library and can be selected by using an empty argument to this
     command.  Only lower the default (for example to 512 bits) if there
     is no other way to make TLS work with the remote server.  *Note
     Transport Layer Security::.
‘tls_priorities [PRIORITIES]’
     Set the priorities for TLS sessions.  The default is set by the TLS
     library and can be selected by using an empty argument to this
     command.  Currently this command only works with sufficiently
     recent GnuTLS releases.  See the GnuTLS documentation of the
     ‘gnutls_priority_init’ function for a description of the PRIORITIES
     string.  *Note Transport Layer Security::.

2.4 Commands specific to sendmail mode
======================================

*Note Sendmail mode::.

‘auto_from [(on|off)]’
     Enable or disable automatic envelope-from addresses.  The default
     is ‘off’.
     When enabled, an envelope-from address of the form user@domain will
     be generated.  The local part will be set to ‘USER’ or, if that
     fails, to ‘LOGNAME’ or, if that fails, to the login name of the
     current user.  The domain part can be set with the ‘maildomain’
     command (see *note maildomain::).  If the maildomain is empty, the
     envelope-from address will only consist of the user name and not
     have a domain part.
     When disabled, the envelope-from address must be set explicitly
     with the ‘from’ command (see *note from::).
     *Note Envelope-from address::.
‘from [ADDRESS]’
     Set the envelope-from address.  This address will only be used when
     ‘auto_from’ is disabled.  *Note Envelope-from address::.
‘maildomain [DOMAIN]’
     Set a domain part for the generation of an envelope-from address.
     This is only used when ‘auto_from’ is enabled.  The domain may be
     empty.  *Note Envelope-from address::.
‘dsn_notify (off|CONDITION)’
     This command sets the condition(s) under which the mail system
     should send DSN (Delivery Status Notification) messages.  The
     argument off disables explicit DSN requests, which means the mail
     system decides when to send DSN messages.  This is the default.
     The CONDITION must be ‘never’, to never request notification, or a
     comma separated list (no spaces!)  of one or more of the following:
     ‘failure’, to request notification on transmission failure,
     ‘delay’, to be notified of message delays, ‘success’, to be
     notified of successful transmission.  The SMTP server must support
     the DSN extension.  *Note Delivery Status Notifications::.
‘dsn_return (off|AMOUNT)’
     This command controls how much of a mail should be returned in DSN
     (Delivery Status Notification) messages.  The argument off disables
     explicit DSN requests, which means the mail system decides how much
     of a mail it returns in DSN messages.  This is the default.  The
     AMOUNT must be ‘headers’, to just return the message headers, or
     ‘full’, to return the full mail.  The SMTP server must support the
     DSN extension.  *Note Delivery Status Notifications::.
‘keepbcc [(on|off)]’
     This command controls whether to remove or keep the Bcc header when
     sending a mail.  The default is to remove it.  *Note Bcc header::.
‘logfile [FILE]’
     This command enables or disables logging to the specified file.  An
     empty argument disables this feature.  The file name ‘-’ directs
     the log information to standard output.  *Note Logging::.
‘syslog [(on|off|FACILITY)]’
     This command enables or disables syslog logging.  The facility can
     be one of ‘LOG_USER’, ‘LOG_MAIL’, ‘LOG_LOCAL0’, …, ‘LOG_LOCAL7’.
     The default facility is ‘LOG_USER’.  Syslog logging is disabled by
     default.  *Note Logging::.
‘aliases [FILE]’
     Replace local recipients with addresses in the aliases file.  The
     aliases file is a plain text file containing mappings between a
     local address and a list of domain addresses.  A local address is
     defined as one without an ’@’ character and a domain address is one
     with an ’@’ character.  The mappings are of the form:
          local: someone@example.com, person@domain.example
     Multiple domain addresses are separated with commas.  Comments
     start with ’#’ and continue to the end of the line.
     The local address ‘default’ has special significance and is matched
     if the local address is not found in the aliases file.  If no
     ‘default’ alias is found, then the local address is left as is.
     An empty argument to the aliases command disables the replacement
     of local addresses.  This is the default.


File: msmtp.info,  Node: Invocation,  Next: Transport Layer Security,  Prev: Configuration files,  Up: Top

3 Invocation
************

3.1 Synopsis
============

   • Sendmail mode (default):
     ‘msmtp [OPTION…] [--] RECIPIENT…’
     ‘msmtp [OPTION…] -t [--] [RECIPIENT…]’
   • Server information mode:
     ‘msmtp [OPTION…] --serverinfo’
   • Remote Message Queue Starting mode:
     ‘msmtp [OPTION…] --rmqs=(HOST|@DOMAIN|#QUEUE)’

3.2 Options
===========

Options override configuration file settings.  They are compatible with
sendmail where appropriate.

3.2.1 General options
---------------------

‘--version’
     Print version information.  This includes information about the
     library used for TLS/SSL support (if any), the library used for
     authentication, the authentication mechanisms supported by this
     library, and the default locations of the system and user
     configuration files.
‘--help’
     Print help.
‘-P’
‘--pretend’
     Print the configuration settings that would be used, but do not
     take further action.  An asterisk (’*’) will be printed instead of
     the password.
‘-v’
‘-d’
‘--debug’
     Print lots of debugging information, including the whole
     conversation with the SMTP server.  Be careful with this option:
     the (potentially dangerous) output will not be sanitized, and your
     password may get printed in an easily decodable format!

3.2.2 Changing the mode of operation
------------------------------------

‘-S’
‘--serverinfo’
     Print information about the SMTP server and exit.  This includes
     information about supported features (mail size limit,
     authentication, TLS, DSN, …) and about the TLS certificate (if TLS
     is active).  *Note Server information mode::.
‘--rmqs=(HOST|@DOMAIN|#QUEUE)’
     Send a Remote Message Queue Starting request for the given host,
     domain, or queue to the SMTP server and exit.  *Note Remote Message
     Queue Starting mode::.

3.2.3 Configuration options
---------------------------

Most options in this category correspond to a configuration file
command.  Please refer to *note Configuration files:: for detailed
information.
‘-C FILENAME’
‘--file=FILENAME’
     Use the given file instead of ‘~/.msmtprc’ as the user
     configuration file.
‘-a ACCOUNT’
‘--account=ACCOUNT’
     Use the given account instead of the account named ‘default’.  This
     option cannot be used together with the ‘--host’ option.  *Note
     Choosing an account::.
‘--host=HOSTNAME’
     Use this SMTP server with settings from the command line; do not
     use any configuration file data.  This option cannot be used
     together with the ‘--account’ option.  It disables loading of
     configuration files.  *Note Choosing an account::.
‘--port=NUMBER’
     Set the port number to connect to.  *Note port::.
‘--timeout=(off|SECONDS)’
     Set a network timeout.  *Note timeout::.  For compatibility with
     older versions, ‘--connect-timeout’ is accepted as an alias for
     this option.
‘--protocol=(smtp|lmtp)’
     Set the protocol.  *Note protocol::.
‘--domain=[ARGUMENT]’
     Set the argument of the SMTP EHLO (or LMTP LHLO) command.  *Note
     domain::.
‘--auth[=(on|off|METHOD)]’
     Enable or disable authentication and optionally choose the method.
     *Note auth::.
‘--user=[USERNAME]’
     Set or unset the user name for authentication.  *Note user::.
‘--passwordeval=[EVAL]’
     Evaluate password for authentication.  *Note passwordeval::.
‘--tls[=(on|off)]’
     Enable or disable TLS/SSL. *Note tls::.
‘--tls-starttls[=(on|off)]’
     Enable or disable STARTTLS for TLS encryption.  *Note
     tls_starttls::.
‘--tls-trust-file=[FILE]’
     Set or unset a trust file for TLS encryption.  *Note
     tls_trust_file::.
‘--tls-crl-file=[FILE]’
     Set or unset a certificate revocation list (CRL) file for TLS.
     *Note tls_crl_file::.
‘--tls-fingerprint=[FINGERPRINT]’
     Set ot unset the fingerprint of a trusted TLS certificate.  *Note
     tls_fingerprint::.
‘--tls-key-file=[FILE]’
     Set or unset a key file for TLS encryption.  *Note tls_key_file::.
‘--tls-cert-file=[FILE]’
     Set or unset a cert file for TLS encryption.  *Note
     tls_cert_file::.
‘--tls-certcheck[=(on|off)]’
     Enable or disable server certificate checks for TLS encryption.
     *Note tls_certcheck::.
‘--tls-force-sslv3[=(on|off)]’
     Force TLS/SSL version SSLv3.  *Note tls_force_sslv3::.
‘--tls-min-dh-prime-bits=[BITS]’
     Set or unset minimum bit size of the Diffie-Hellman (DH) prime.
     *Note tls_min_dh_prime_bits::.
‘--tls-priorities=[PRIORITIES]’
     Set or unset TLS priorities.  *Note tls_priorities::.

3.2.4 Options specific to sendmail mode
---------------------------------------

‘--auto-from[=(on|off)]’
     Enable or disable automatic envelope-from addresses.  The default
     is off.  *Note auto_from::.
‘-f ADDRESS’
‘--from=ADDRESS’
     Set the envelope-from address.  It is only used when ‘auto_from’ is
     off.  *Note from::.
     If no account was chosen yet (with ‘--account’ or ‘--host’), this
     option will choose the first account that has the given
     envelope-from address (set with the ‘from’ command).  If no such
     account is found, "default" is used.  *Note Choosing an account::.
‘--maildomain=[DOMAIN]’
     Set the domain part for generated envelope-from addresses.  It is
     only used when ‘auto_from’ is on.  *Note maildomain::.
‘-N (off|CONDITION)’
‘--dsn-notify=(off|CONDITION)’
     Set or unset DSN notification conditions.  *Note dsn_notify::.
‘-R (off|AMOUNT)’
‘--dsn-return=(off|AMOUNT)’
     Set or unset the DSN notification amount.  *Note dsn_return::.
     Note that ‘hdrs’ is accepted as an alias for ‘headers’ to be
     compatible with sendmail.
‘--keepbcc[=(on|off)]’
     Enable or disable the preservation of the Bcc header.  *Note
     keepbcc::.
‘-X [FILE]’
‘--logfile=[FILE]’
     Set or unset the log file.  *Note logfile::.
‘--syslog[=(on|off|FACILITY)]’
     Enable or disable syslog logging.  *Note syslog::.
‘-t’
‘--read-recipients’
     Send the mail to the recipients given in the To, Cc, and Bcc
     headers of the mail in addition to the recipients given on the
     command line.
     If any Resent- headers are present, then the addresses from any
     Resent-To, Resent-Cc, and Resent-Bcc headers in the first block of
     Resent- headers are used instead.
‘--read-envelope-from’
     Read the envelope from address from the From header of the mail.
     Currently this header must be on a single line for this option to
     work correctly.
‘--aliases=[FILE]’
     Set or unset an aliases file.  *Note aliases::.
‘--’
     This marks the end of options.  All following arguments will be
     treated as recipient addresses, even if they start with a ’-’.

   The following options are accepted but ignored for sendmail
compatibility: ‘-BTYPE’, ‘-bm’, ‘-FNAME’, ‘-G’, ‘-hN’, ‘-i’, ‘-L TAG’,
‘-m’, ‘-n’, ‘-O option=VALUE’, ‘-ox VALUE’

3.3 Choosing an account
=======================

There are three ways to choose the account to use.  It depends on the
circumstances which method is the best.

  1. ‘--account=ACCOUNT’
     Use the given account.  Command line settings override
     configuration file settings.
  2. ‘--host=HOSTNAME’
     Use only the settings from the command line; do not use any
     configuration file data.
  3. ‘--from=ADDRESS’ or ‘--read-envelope-from’
     Choose the first account from the system or user configuration file
     that has a matching envelope-from address as specified by a ‘from’
     command.  This works only when neither ‘--account’ nor ‘--host’ is
     used.
   If none of the above options is used (or if no account has a matching
‘from’ command), then the account "default" is used.

3.4 Exit code
=============

The standard exit codes from ‘sysexits.h’ are used.

3.5 Files
=========

‘‘SYSCONFDIR/msmtprc’’
     The system configuration file.  Use the ‘--version’ option to find
     out what ‘SYSCONFDIR’ is on your platform.
‘‘~/.msmtprc’’
     The default user configuration file.
‘‘~/.netrc’ and ‘SYSCONFDIR/netrc’’
     The ‘netrc’ file contains login information.  If a password is not
     found in the configuration file, msmtp will search it in ‘~/.netrc’
     and ‘SYSCONFDIR’ before prompting the user for it.  The syntax of
     ‘netrc’ files is described in the ‘netrc(5)’ or ‘ftp(1)’ manual
     page.

3.6 Environment
===============

‘‘USER’, ‘LOGNAME’’
     These variables override the user’s login name when constructing an
     envelope-from address.  ‘LOGNAME’ is only used if ‘USER’ is unset.
‘‘TMPDIR’’
     Directory to create temporary files in.  If this is unset, a system
     specific default directory is used.
     A temporary file is only created when the ‘-t’/‘--read-recipients’
     or ‘--read-envelope-from’ option is used.  The file is then used to
     buffer the headers of the mail (but not the body, so the file won’t
     get very large).
‘‘EMAIL’, ‘SMTPSERVER’’
     These environment variables are used only if neither ‘--host’ nor
     ‘--account’ is used and there is no default account defined in the
     configuration files.  In this case, the host name is taken from
     ‘SMTPSERVER’, and the envelope from address is taken from ‘EMAIL’,
     unless overridden by ‘--from’ or ‘--read-envelope-from’.  Currently
     ‘SMTPSERVER’ must contain a plain host name (no URL), and ‘EMAIL’
     must contain a plain address (no names or additional information).


File: msmtp.info,  Node: Transport Layer Security,  Next: Authentication,  Prev: Invocation,  Up: Top

4 Transport Layer Security
**************************

Transport Layer Security (TLS) is a new name for Secure Socket Layer
(SSL). The TLS 1.0 protocol is an updated version of the SSL 3.0
protocol.  TLS and SSL mean the same thing.

   Quoting from RFC2246, the TLS 1.0 protocol specification:
"The TLS protocol provides communications privacy over the Internet.
The protocol allows client/server applications to communicate in a way
that is designed to prevent eavesdropping, tampering, or message
forgery."

   SMTP servers can use TLS in one of two modes:
   • Immediately.  This is SMTP tunneled through TLS, aka SSMTP. The
     default port for this mode is 465 (smtps).
   • Via the STARTTLS SMTP command.  The SMTP session begins normally.
     The client sends the STARTTLS command when it wishes to begin TLS
     encryption.  The default port for this mode is the default SMTP
     port: 25 (smtp).
   msmtp can switch between these modes with the ‘tls_starttls’ command
(see *note tls_starttls::) command or the ‘--tls-starttls’ option (see
*note --tls-starttls::).

   When TLS is started, the server sends a certificate to identify
itself.  This certificate contains information about the certificate
owner, the certificate issuer, and the activation and expiration times
of the certificate.  This information can be displayed in server
information mode.  *Note Server information mode::.

   To use TLS, it is required to either enable full server certificate
verification using the ‘tls_trust_file’ command or ‘--tls-trust-file’
option, or to trust one particular peer certificate using the
‘tls_fingerprint’ command or ‘--tls-fingerprint’ option, or to disable
all certificate checks using ‘tls_certcheck off’ or
‘--tls-certcheck=off’.  WARNING: When certificate checks are disabled,
TLS/SSL sessions are vulnerable to man-in-the-middle attacks!  See *note
tls_trust_file::, *note --tls-trust-file::, *note tls_fingerprint::,
*note --tls-fingerprint::, *note tls_certcheck::, *note
--tls-certcheck::.

   If your system has a file that collects all system-wide trusted CA
certificates, it is easiest to just use this in the ‘defaults’ section
of your configuration file.  On Debian-based systems, for example, the
adequate command would be ‘tls_trust_file
/etc/ssl/certs/ca-certificates.crt’.

   But you can also find out manually which CA certificate you need to
trust.  First, issue the following command:
     $ msmtp --serverinfo --host=smtp.example.com --tls=on --tls-certcheck=off
   The option ‘--tls-certcheck=off’ allows msmtp to accept any
certificate, so that it can print some information about it.  The output
of this command tells you the common name of the server certificate
issuer.  You have to trust this issuer to use full TLS security.
Usually you can find the CA certificate on the issuer’s homepage.  With
this CA certificate, the following should succeed:
     $ msmtp --serverinfo --host=smtp.example.com --tls=on \
       --tls-trust-file=ca_cert.txt

   If the server requests it, the client can send a certificate, too.
This allows the server to verify the identity of the client.  See the
EXTERNAL mechanism in *note Authentication::.  The
‘tls_key_file’/‘tls_cert_file’ commands or the
‘--tls-key-file’/‘--tls-cert-file’ options can be used to set a client
certificate.  See *note tls_key_file::/*note --tls-key-file::, *note
tls_cert_file::/*note --tls-cert-file::.  Note that GnuTLS will only
send a client certificate if it matches one of the CAs advertised by the
server.  If you set a client certificate but it is not sent to the
server, it probably was not issued by any CA that the server trusts.

   If you need to fine tune TLS parameters or have problems connecting
to your server, have a look at the *note tls_force_sslv3::, *note
tls_min_dh_prime_bits::, and *note tls_priorities:: commands.


File: msmtp.info,  Node: Authentication,  Next: Delivery Status Notifications,  Prev: Transport Layer Security,  Up: Top

5 Authentication
****************

Many SMTP servers require a client to authenticate itself before it is
allowed to send mail.

   Multiple authentication methods exist.  Most SMTP servers support
only some of them.  Some methods send authentication data in plain text
(or nearly plain text) to the server.  These methods should only be used
when TLS is active to prevent others from stealing the password.  *Note
Transport Layer Security::.

   By default, msmtp chooses a method automatically, and it will never
choose one that puts the authentication data at risk.  See below for
details.

   msmtp supports the following authentication methods:
   • ‘PLAIN’
     This authentication method needs a user name and a password.  Both
     are send in BASE64 encoding, which can be easily decoded to plain
     text.
   • ‘SCRAM-SHA-1’
     This authentication method needs a user name and a password.  The
     authentication data is not sent in plain text, which means this
     method can safely be used without TLS.
   • ‘CRAM-MD5’
     This authentication method needs a user name and a password.  The
     authentication data is not sent in plain text, which means this
     method can safely be used without TLS.
   • ‘GSSAPI’
     This authentication method needs a user name.  The Kerberos
     framework takes care of secure authentication, therefore this
     method can safely be used without TLS.
   • ‘EXTERNAL’
     This is a special authentication method: The actual authentication
     happens outside of the SMTP protocol, typically by sending a TLS
     client certificate (see *note Transport Layer Security::).
     The EXTERNAL method merely confirms that this authentication
     succeeded for the given user (or, if no user name is given,
     confirms that authentication succeeded).  Thus it may not be
     necessary for authentication to use this method, and if the server
     does not support the EXTERNAL method, this does not mean that it
     does not support authentication with TLS client certificates.
     This authentication method is not chosen automatically; you have to
     request it manually.
     Note: Sendmail 8.12.11 advertises the EXTERNAL mechanism only after
     a TLS client certificate has been send.  It seems to ignore the
     optional user name.  Does anyone know more about this?
   • ‘DIGEST-MD5’
     This is an obsolete authentication method needs a user name and a
     password.  The authentication data is not sent in plain text, but
     the encryption based on MD5 is not considered secure anymore.
   • ‘LOGIN’
     This is a non-standard authentication method similar to (but worse
     than) PLAIN. It needs a user name and a password, both of which are
     send in BASE64 encoding, which can be easily decoded to plain text.
   • ‘NTLM’
     This is an obscure non-standard authentication method.  It needs a
     user name and a password and in some cases a special domain
     parameter (see *note ntlmdomain::).  The authentication data is not
     send in plain text, but since NTLM is not an open standard, it
     should be considered broken and insecure.

   It depends on the underlying authentication library and its version
whether a particular method is supported or not.  Use the ‘--version’ to
find out which methods are supported by your version of msmtp.

   Authentication data can be set with the ‘user’ and ‘password’
commands or with the ‘--user’ option.  See *note user::, *note
password::, *note --user::.  If no password is set but one is needed
during authentication, msmtp will try to find it.  First, if
‘passwordeval’ is set, it will evaluate that command.  If ‘passwordeval’
is not set, msmtp will try to find the password in ‘~/.netrc’.  If that
fails, it will try to find it in ‘SYSCONFDIR/netrc’ (use ‘--version’ to
find out what ‘SYSCONFDIR’ is on your platform).  If that fails, it will
try to get it from a system specific keyring (if available).  If that
fails but a controlling terminal is available, msmtp will prompt you for
it.

   Currently supported keyrings are the Gnome Keyring and the Mac OS X
Keychain.  The script ‘msmtp-gnome-tool.py’ can be used to manage Gnome
Keyring passwords for msmtp.  To manage Mac OS X Keychain passwords, use
the Keychain Access GUI application.  The ‘account name’ is same as the
msmtp ‘user’ argument.  The ‘keychain item name’ is ‘smtp://<hostname>’
where ‘<hostname>’ matches the msmtp ‘host’ argument.

   The authentication method can be chosen with the ‘auth’ command or
‘--auth’ option, but it is usually sufficient to just use the ‘on’
argument to let msmtp choose the method itself.  See *note auth::, *note
--auth::.

   If msmtp chooses the method itself, it will never choose an insecure
method.  If TLS is active, all methods are considered secure in this
context, because the connection to the server is protected by TLS. If
TLS is not active, only the SCRAM-SHA-1, CRAM-MD5, and GSSAPI methods
are considered secure in this context, because all the others methods
put the authentication data at risk.

   If you really want to risk your authentication data, you have to
force msmtp to do that by manually setting the authentication method
while TLS is off.


File: msmtp.info,  Node: Delivery Status Notifications,  Next: Sendmail mode,  Prev: Authentication,  Up: Top

6 Delivery Status Notifications
*******************************

In situations such as delivery failure or very long delivery delay, the
mail system often generates a message for the sender of the mail in
question, informing him about the difficulties.

   Delivery Status Notification (DSN) requests, defined in RFC 3461, try
to give the sender of the mail control about how and when these DSN
messages are sent.  The SMTP server must support the DSN extension.
*Note Server information mode::.

   A first parameter controls when such messages should be generated:
never, on delivery failure, on delivery delay, and/or on success.  This
can be set with ‘dsn_notify’/‘--dsn-notify’, see *note
dsn_notify::/*note --dsn-notify::.

   A second parameter controls how much of the original mail should be
contained in a DSN message: only the headers, or the full mail.  This
can be set with ‘dsn_return’/‘--dsn-return’, see *note
dsn_return::/*note --dsn-return::.  Note that this parameter only
applies to DSNs that indicate delivery failure for at least one
recipient.  If a DSN contains no indications of delivery failure, only
the headers of the message are returned.


File: msmtp.info,  Node: Sendmail mode,  Next: Server information mode,  Prev: Delivery Status Notifications,  Up: Top

7 Sendmail mode
***************

* Menu:

* Envelope-from address::	Information about envelope-from addresses
* Logging::			Different logging methods
* Bcc header::			Bcc header handling


File: msmtp.info,  Node: Envelope-from address,  Next: Logging,  Up: Sendmail mode

7.1 Envelope-from address
=========================

The SMTP server expects a sender mail address for each mail.  This is
the envelope-from address.  It is independent of the From header
(because it is part of the mail _envelope_, not of the mail itself), but
in most cases both addresses are the same.

   Envelope-from addresses can be generated automatically (when
‘auto_from’ is enabled with the ‘auto_from’ command or ‘--auto-from’
option) or set explicitly with the ‘from’ command and ‘--from’ option.
See *note auto_from::, *note from::.

   When ‘auto_from’ is enabled, an envelope-from address of the form
user@domain will be generated.  The local part will be set to ‘USER’ or,
if that fails, to ‘LOGNAME’ or, if that fails, to the login name of the
current user.  The domain part can be set with the ‘maildomain’ command
and ‘--maildomain’ option (see *note maildomain::).  If the maildomain
is empty, the envelope-from address will only consist of the user name
and not have a domain part.


File: msmtp.info,  Node: Logging,  Next: Bcc header,  Prev: Envelope-from address,  Up: Sendmail mode

7.2 Logging
===========

Logging is enabled on a per account basis.  If it is enabled, msmtp will
generate one log line for each mail it tries to send via the account in
question.

   The line will include the following information:
   • Host name of the SMTP server: ‘host=hostname’
   • Whether TLS was used: ‘tls=(on|off)’
   • Whether authentication was used: ‘auth=(on|off)’
   • The user name used for authentication (only if authentication is
     used): ‘user=name’
   • The envelope-from address: ‘from=address’
   • The recipient addresses: ‘recipients=addr1,addr2,…’
   • The size of the mail as transferred to the server, in bytes (only
     if the delivery succeeded): ‘mailsize=number’
   • The SMTP status code and SMTP error message (only in case of
     failure and only if available): ‘smtpstatus=number’,
     ‘smtpmsg='message'’.  Multiline SMTP messages will be concatenated
     into one line.
   • The msmtp error message (only in case of failure and only if
     available): ‘errormsg='message'’
   • The msmtp exit code (from ‘sysexits.h’; ‘EX_OK’ indicates success):
     ‘exitcode=EX_…’

   If a logfile is given with the ‘logfile’ command or ‘--logfile’
option, this log line will be prepended with the current date and time
and appended to the specified file.  See *note logfile::, *note
--logfile::.

   If syslog logging is enabled with the ‘syslog’ command or ‘--syslog’
option, the log line is passed to the syslog service with the specified
facility.  See *note syslog::, *note --syslog::.


File: msmtp.info,  Node: Bcc header,  Prev: Logging,  Up: Sendmail mode

7.3 Bcc header
==============

msmtp transmits mails unaltered to the SMTP server, with one exception:
the Bcc header(s) will be removed before the transmission.  This
behavior can be changed with the ‘keepbcc’ command and ‘--keepbcc’
option, see *note keepbcc::/*note --keepbcc::.


File: msmtp.info,  Node: Server information mode,  Next: Remote Message Queue Starting mode,  Prev: Sendmail mode,  Up: Top

8 Server information mode
*************************

In server information mode, msmtp prints as much information about the
SMTP server as it can get and then exits.

   The SMTP features that can be detected are:
   • SIZE
     The maximum message size that the SMTP server accepts.
   • PIPELINING
     Whether certain SMTP commands may be send in groups rather than one
     by one.  This can speed up mail transmission if the recipient list
     is long.  This feature is used automatically.
   • STARTTLS
     *Note Transport Layer Security::.
   • AUTH
     *Note Authentication::.
   • DSN
     *Note Delivery Status Notifications::.
   • ETRN
     *Note Remote Message Queue Starting mode::.

   If TLS is activated for server information mode, the following
information will be printed about the SMTP server’s TLS certificate (if
available):
   • Owner information
        • Common Name
        • Organization
        • Organizational unit
        • Locality
        • State or Province
        • Country
   • Issuer information
        • Common Name
        • Organization
        • Organizational unit
        • Locality
        • State or Province
        • Country
   • General
        • Activation time
        • Expiration time
        • SHA1 fingerprint
        • MD5 fingerprint


File: msmtp.info,  Node: Remote Message Queue Starting mode,  Next: Examples,  Prev: Server information mode,  Up: Top

9 Remote Message Queue Starting mode
************************************

Remote Message Queue Starting (RMQS) is defined in RFC 1985.  It is a
way for a client to request that a server start the processing of its
mail queues for messages that are waiting at the server for the client
machine.  If any messages are at the server for the client, then the
server creates a new SMTP session and sends the messages at that time.

   msmtp can only send the request (using the ETRN SMTP command); a mail
server on the client side should then accept the connection of the
remote SMTP server to receive the mail.

   RMQS requests can be sent with the ‘--rmqs’ option (see *note
--rmqs::).  Destinations defined in RFC 1985 are:
   • HOST
     Request the messages for the given host.
   • @DOMAIN
     Request the messages for the given domain.
   • #QUEUE
     Request the delivery of the messages in the given queue.


File: msmtp.info,  Node: Examples,  Prev: Remote Message Queue Starting mode,  Up: Top

10 Examples
***********

* Menu:

* A system wide configuration file::
* A user configuration file::
* Using msmtp with Mutt::
* Using msmtp with mail::
* Aliases file::


File: msmtp.info,  Node: A system wide configuration file,  Next: A user configuration file,  Up: Examples

10.1 A system wide configuration file
=====================================

     # A system wide configuration is optional.
     # If it exists, it usually defines a default account.
     # This allows msmtp to be used like /usr/sbin/sendmail.
     account default

     # The SMTP smarthost.
     host mailhub.oursite.example

     # Construct envelope-from addresses of the form "user@oursite.example".
     #auto_from on
     #maildomain oursite.example

     # Use TLS.
     #tls on
     #tls_trust_file /etc/ssl/certs/ca-certificates.crt

     # Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
     syslog LOG_MAIL


File: msmtp.info,  Node: A user configuration file,  Next: Using msmtp with Mutt,  Prev: A system wide configuration file,  Up: Examples

10.2 A user configuration file
==============================

     # Set default values for all following accounts.
     defaults
     tls on
     tls_trust_file /etc/ssl/certs/ca-certificates.crt
     logfile ~/.msmtp.log

     # A freemail service
     account freemail
     host smtp.freemail.example
     from joe_smith@freemail.example
     auth on
     user joe.smith
     password secret

     # A second mail address at the same freemail service
     account freemail2 : freemail
     from joey@freemail.example

     # The SMTP server of the provider.
     account provider
     host mail.provider.example
     from smithjoe@provider.example
     auth on
     user 123
     passwordeval gpg -d ~/.msmtp.password.gpg

     # Set a default account
     account default : provider


File: msmtp.info,  Node: Using msmtp with Mutt,  Next: Using msmtp with mail,  Prev: A user configuration file,  Up: Examples

10.3 Using msmtp with Mutt
==========================

Create a configuration file for msmtp and add the following lines to
your Mutt configuration file:
     set sendmail="/path/to/msmtp"
     set use_from=yes
     set realname="Your Name"
     set from=you@example.com
     set envelope_from=yes

   The ‘envelope_from=yes’ option lets Mutt use the ‘-f’ option of
msmtp.  Therefore msmtp chooses the first account that matches the from
address you@example.com.  Alternatively, you can use the ‘-a’ option:
     set sendmail="/path/to/msmtp -a my_account"

   Or set everything from the command line:
     set sendmail="/path/to/msmtp --host=mailhub -f me@example.com --tls"
   *Note Choosing an account::.

   If you have multiple mail accounts in your msmtp configuration file
and let Mutt use the ‘-f’ option to choose one, you can easily switch
accounts in Mutt with the following Mutt configuration lines:
     macro generic "<esc>1" ":set from=you@example.com"
     macro generic "<esc>2" ":set from=you@your-employer.example"
     macro generic "<esc>3" ":set from=you@some-other-provider.example"
   Now you can use <esc>1, <esc>2, and <esc>3 to switch accounts.

   The following example uses a different approach: it maps the single
key ‘<tab>’ in Compose context for switching between the various account
in a handy visual way.  In the same Compose context, ‘=’ is mapped in
order to show the current msmtp account.  This example was contributed
by Thomas Baruchel.
     # Define <tab> and = in order to switch or see the current msmtp account
     # Don't forget to put the right path for msmtp binary
     macro compose \Cx_ ":set sendmail"
     macro compose \Cx| "\Cx_ = \"/usr/local/bin/msmtp"
     macro compose \Cx& ":macro compose \\t \\Cx"
     macro compose <tab> "\Cx0"
     macro compose = "\Cx_\n"
     # Put the account in the following lines (here three accounts)
     # Don't forget to put the number of the account at the beginning
     # of the line, and the number of the next account after the '&'
     macro compose \Cx0 "\Cx|\"\n\Cx&1\n\Cx_\n" # default and switch to 1
     macro compose \Cx1 "\Cx| -a example_account\"\n\Cx&2\n\Cx_\n" # switch to 2
     macro compose \Cx2 "\Cx| -a gmail\"\n\Cx&0\n\Cx_\n" # switch to 0
     # End of the accounts


File: msmtp.info,  Node: Using msmtp with mail,  Next: Aliases file,  Prev: Using msmtp with Mutt,  Up: Examples

10.4 Using msmtp with mail
==========================

Define a default account, and put the following into ‘~/.mailrc’:
     set sendmail="/path/to/msmtp"

   You need to define a default account, because mail does not allow
extra options to the msmtp command line.


File: msmtp.info,  Node: Aliases file,  Prev: Using msmtp with mail,  Up: Examples

10.5 Aliases file
=================

     # Example aliases file

     # Send root to Joe and Jane
     root: joe_smith@example.com, jane_chang@example.com

     # Send cron to Mark
     cron: mark_jones@example.com

     # Send everything else to admin
     default: admin@domain.example



Tag Table:
Node: Top629
Node: Introduction1659
Node: Configuration files3585
Ref: defaults5157
Ref: account5335
Ref: host5710
Ref: port5890
Ref: timeout6207
Ref: protocol6527
Ref: domain6698
Ref: auth7229
Ref: user7687
Ref: password7871
Ref: passwordeval8688
Ref: ntlmdomain8815
Ref: tls9128
Ref: tls_trust_file9532
Ref: tls_crl_file9940
Ref: tls_fingerprint10282
Ref: tls_key_file10907
Ref: tls_cert_file11242
Ref: tls_certcheck11553
Ref: tls_starttls11936
Ref: tls_force_sslv312256
Ref: tls_min_dh_prime_bits12471
Ref: tls_priorities12897
Ref: auto_from13435
Ref: from14168
Ref: maildomain14328
Ref: dsn_notify14544
Ref: dsn_return15279
Ref: keepbcc15807
Ref: logfile15977
Ref: syslog16208
Ref: aliases16509
Node: Invocation17407
Ref: --serverinfo18953
Ref: --rmqs19235
Ref: --auth20725
Ref: --user20847
Ref: --passwordeval20938
Ref: --tls-starttls21100
Ref: --tls-trust-file21212
Ref: --tls-crl-file21323
Ref: --tls-fingerprint21446
Ref: --tls-key-file21579
Ref: --tls-cert-file21679
Ref: --tls-certcheck21787
Ref: --tls-force-sslv321917
Ref: --tls-min-dh-prime-bits22012
Ref: --tls-priorities22154
Ref: --auto-from22332
Ref: --from22464
Ref: --maildomain22890
Ref: --dsn-notify23053
Ref: --dsn-return23181
Ref: --keepbcc23408
Ref: --logfile23517
Ref: --syslog23606
Ref: Choosing an account24702
Ref: Files25620
Ref: Environment26234
Node: Transport Layer Security27410
Node: Authentication31433
Node: Delivery Status Notifications36905
Node: Sendmail mode38203
Node: Envelope-from address38513
Node: Logging39643
Node: Bcc header41365
Node: Server information mode41731
Node: Remote Message Queue Starting mode43207
Node: Examples44254
Node: A system wide configuration file44515
Node: A user configuration file45270
Node: Using msmtp with Mutt46199
Node: Using msmtp with mail48636
Node: Aliases file49024

End Tag Table


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