This manual was last updated 27 September 2023 for version 1.8.25 of msmtp.
Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023
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.
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.
The best way to start is probably to have a look at the Examples section. See Examples.
In addition to sendmail mode, there are two other modes of operation:
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 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.
Supported features include:
A suggestion for a suitable configuration file can be generated using the ‘--configure’ option; see --configure.
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. Use --version to find out
which SYSCONFDIR your version of msmtp uses.
The default user configuration file is ~/.msmtprc or
$XDG_CONFIG_HOME/msmtp/config. Accounts defined in the user
configuration file override accounts from the system configuration file.
Configuration file settings can be changed by command line options.
A configuration file is a simple text file. Empty lines and comment lines (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 a file name starts with 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 are organized in accounts. Each account starts with the ‘account’ command and defines the settings for one SMTP account.
See Examples.
Set defaults. The following commands will set default values for all following account definitions in the current configuration file.
Start a new account definition with the given name. The current default values
are filled in (see 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.
Replace the current configuration file line with the first line of the output
(stdout) of the command cmd. This can be used to decrypt settings or to
create them via scripts. For example, eval echo host localhost replaces
the current line with host localhost.
Note that every ‘eval’ line will be evaluated when the configuration
file is read.
The cmd command must not mess with standard input; if in doubt, append
< /dev/null.
Note that for passwords you can also use the passwordeval command instead
of eval password cmd. This has the advantage that the command is only
evaluated if needed.
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.
The port that the SMTP server listens on. The default is 25 ("smtp"), unless TLS without STARTTLS is used, in which case it is 465 ("smtps").
Set a source IP address to bind the outgoing connection to. Useful only in special cases on multi-home systems. An empty argument disables this.
Use a SOCKS proxy. All network traffic will go through this proxy host, including DNS queries, except for a DNS query that might be necessary to resolve the proxy host name itself (this can be avoided by using an IP address as proxy host name). An empty argument disables proxy usage. The supported SOCKS protocol version is 5. If you plan to use this with Tor, see also Using msmtp with Tor.
Set the port number for the proxy host. An empty ‘number’ argument resets this to the default port, which is 1080 ("socks").
Set the file name of a unix domain socket to connect to. This overrides both ‘host’/‘port’ and ‘proxy_host’/‘proxy_port’.
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.
Set the protocol to use. Currently only SMTP and LMTP are supported. SMTP is the default. See port for default ports.
This command sets the argument of the SMTP EHLO (or LMTP LHLO) command,
and the domain part of Message-ID headers if msmtp generates them (see
set_msgid_header).
The default value ‘localhost’ is stupid but usually works for EHLO. However
it does not make sense for Message-ID headers. See set_msgid_header for details.
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).
The following substitution patterns are supported:
%H will be replaced by $HOSTNAME, or if that fails by the host name of the system.
%C will be replaced by the canonical name of %H.
%M will be replaced by the contents of /etc/mailname (potentially a different
directory is used depending on the build configuration; see the output of
‘msmtp --version’ and look for the location of the system configuration file).
See Authentication.
Enable or disable authentication and optionally choose a method to use. The
argument ‘on’ chooses a method automatically.
Accepted methods are ‘plain’, ‘scram-sha-1’, ‘scram-sha-256’, ‘oauthbearer’, ‘xoauth2’, ‘cram-md5’,
‘gssapi’, ‘external’, ‘digest-md5’, ‘login’, and
‘ntlm’.
See Authentication.
Set the user name for authentication. An empty argument unsets the user name. Authentication must be activated with the ‘auth’ command.
Set the password for authentication. An empty argument unsets the password. Consider using the ‘passwordeval’ command or a key ring instead of this command, to avoid storing cleartext passwords in the configuration file. See Authentication.
Set the password for authentication to the output (stdout) of the command
cmd.
This can be used e.g. to decrypt password files on the fly or to query key
rings, and thus to avoid storing cleartext passwords.
The cmd command must not mess with standard input; if in doubt, append
< /dev/null.
See Authentication.
Set a domain for the ‘ntlm’ authentication method. This is obsolete.
Enable or disable TLS (also known as SSL) for secured connections.
Choose the TLS variant: start TLS from within the session (‘on’, default), or tunnel the session through TLS (‘off’).
Activate server certificate verification using a list of trusted Certification Authorities (CAs). The default is the special value ‘system’, which selects the system default. An empty argument disables trust in CAs. If you select a file, it must be in PEM format, and you should also use ‘tls_crl_file’.
Deprecated. This sets a certificate revocation list (CRL) file for TLS, to check for revoked certificates (an empty argument, which is the default, disables this). Nowadays automatic OCSP checks replace CRL file checks.
Set the fingerprint of a single certificate to accept for TLS. This certificate
will be trusted regardless of its contents (this overrides ‘tls_trust_file’).
The fingerprint should be of type SHA256, but can for backwards compatibility
also be of type SHA1 or MD5 (please avoid this).
The format should be 01:23:45:67:….
Use ‘--serverinfo --tls --tls-certcheck=off --tls-fingerprint=’
to get the server certificate fingerprint.
Send a client certificate to the server (use this together with ‘tls_cert_file’). The file must contain the private key of a certificate in PEM format. An empty argument disables this feature.
Send a client certificate to the server (use this together with ‘tls_key_file’). The file must contain a certificate in PEM format. An empty argument disables this feature.
Enable or disable checks of the server certificate. They are enabled by default.
Disabling them will override ‘tls_trust_file’ and ‘tls_fingerprint’.
WARNING: When the checks are disabled, TLS sessions will not be secure!
Set priorities for TLS session parameters. The default is set by the TLS library and
can be selected by using an empty argument to this command. The interpretation of the
priorities string depends on the TLS library. Use ‘--version’ to find out
which TLS library you use.
For GnuTLS, see the section on Priority Strings in the manual.
For libtls, the priorites string is a space-separated list of parameter strings
prefixed with either PROTOCOLS=, CIPHERS=, or ECDHECURVES=.
These parameter strings will be passed to the functions ‘tls_config_parse_protocols’,
‘tls_config_set_ciphers’, and ‘tls_config_set_ecdhecurves’.
Unrecognized parts of the priorities string will be ignored. Example:
PROTOCOLS=TLSv1.3 CIPHERS=ECDHE-RSA-AES128-SHA256 ECDHECURVES=P-384.
By default, TLS host verification uses the host name given by the ‘host’ command. This command allows one to use a different host name for verification. This is only useful in special cases.
Deprecated, use ‘tls_priorities’ instead. Set or unset the minimum number of Diffie-Hellman (DH) prime bits accepted 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.
See Sendmail mode.
Set the envelope-from address. The following substitution patterns are supported:
%U will be replaced by $USER, or if that fails by $LOGNAME, or if that fails by
the login name of the user running msmtp.
%H will be replaced by $HOSTNAME, or if that fails by the host name of the system.
%C will be replaced by the canonical name of %H.
%M will be replaced by the contents of /etc/mailname (potentially a different
directory is used depending on the build configuration; see the output of
‘msmtp --version’ and look for the location of the system configuration file).
Note that the obsolete ‘auto_from’ command replaces this envelope-from address.
To enforce the use of this envelope-from address and ignore the ‘-f’ / ‘--from’ option,
see allow_from_override.
See Envelope-from address.
Furthermore, the envelope-from address may be a wildcard pattern as used for file name matching
in the shell. This is the case if it contains one of the characters ?, * or [.
This allows a variety of envelope-from addresses given with the ‘--from’ option to match a single account.
Set a full name to be used in a From header if msmtp adds one. See set_from_header.
By default, the --from option overrides the from command. Set to ‘off’ to disable this.
Set 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. See Delivery Status Notifications.
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. See Delivery Status Notifications.
When to set a From header: ‘auto’ adds a From header if the mail does not
have one (this is the default), ‘on\’ always sets a From header and overrides
any existing one, and ‘off’ never sets a From header.
If the mail server rejects the mail because its From header does not match the
envelope from address (a common anti-spam measure), then you might want to set
this option to ‘on’.
The From header is created based on the envelope-from address. Disable
allow_from_override to prevent programs from setting their own
envelope-from address.
For compatibility with older versions, ‘add_missing_from_header [(on|off)]’
is still supported and corresponds to the ‘auto’ and ‘off’ settings.
See Header handling.
When to set a Date header: ‘auto’ adds a Date header if the mail does not
have one (this is the default), and ‘off’ never sets a Date header.
For compatibility with older versions, ‘add_missing_date_header [(on|off)]’
is still supported and corresponds to the ‘auto’ and ‘off’ settings.
See Header handling.
When to set a Message-ID header: ‘auto’ adds a Message-ID header if the mail does not
have one (this is the default), and ‘off’ never sets a Message-ID header.
Message-IDs have the form ‘hash@domain’, where ‘hash’ is a hash over
some values that uniquely identify the mail, and ‘domain’ is either the
value of the domain command (unless that is the default value
‘localhost’), or the domain part of the envelope-from address (if available),
or the host name of the SMTP server.
See Header handling.
This command controls whether to remove Bcc headers. The default is to remove them.
When set, the original To, Cc, and Bcc headers of the mail are removed and a single new header line "To: undisclosed-recipients:;" is added. The default setting is off. See Header handling.
Enable logging to the specified file. An empty argument disables logging. The file name ‘-’ directs the log information to standard output. See Logging.
Set or unset the log file time format. This will be used as the format string for the strftime() function. An empty argument chooses the default (‘"%b %d %H:%M:%S"’). See Logging.
Enable or disable syslog logging. The facility can be one of ‘LOG_USER’, ‘LOG_MAIL’, ‘LOG_LOCAL0’, …, ‘LOG_LOCAL7’. The default is ‘LOG_USER’. Syslog logging is disabled by default. See Logging.
Replace local recipients with addresses in the aliases file. The aliases file is a cleartext file containing mappings between a local address and a list of replacement addresses. The mappings are of the form:
local: someone@example.com, person@domain.example
Multiple replacement 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.
Note that alias expansion only affects the mail envelope. The To and Cc headers
are not modified.
An empty argument to the aliases command disables the replacement of local
addresses. This is the default.
Obsolete; you can achieve the same and more using the substitution patterns of the
‘from’ command.
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; if that is empty,
the address not have a domain part.
See Envelope-from address.
Obsolete; you can achieve the same and more using the substitution patterns of the
‘from’ command.
Set a domain part for the generation of an envelope-from address. See auto_from.
msmtp [option…] [--] recipient…msmtp [option…] -t [--] [recipient…]
msmtp --configure mailaddressmsmtp [option…] --serverinfo
msmtp [option…]
--rmqs=(host|@domain|#queue)
Options override configuration file settings. They are compatible with sendmail where appropriate.
Print version information, including information about the libraries used.
Print help.
Print the configuration settings that would be used, but do not take further action. An asterisk (’*’) will be printed instead of the password.
Print lots of debugging information, including the whole conversation with the 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!
Generate a configuration for the given mail address and print it. This can be modified or copied unchanged to the configuration file. Note that this only works for mail domains that publish appropriate SRV records; see RFC 8314.
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). See Server information mode.
Send a Remote Message Queue Starting request for the given host, domain, or queue to the SMTP server and exit. See Remote Message Queue Starting mode.
Most options in this category correspond to a configuration file command. Please refer to Configuration files for detailed information.
Use the given file instead of ~/.msmtprc or
XDG_CONFIG_HOME/msmtp/config as the user configuration file.
Use the given account instead of the account named ‘default’. This option cannot be used together with the --host option. See Choosing an account.
Use this 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. See Choosing an account.
Set the port number to connect to. See port.
Set or unset an IP address to bind the socket to. See source_ip.
Set or unset a SOCKS proxy to use. See proxy_host.
Set or unset a port number for the proxy host. See proxy_port.
Set or unset a local unix domain socket name to connect to. See socket.
Set or unset a network timeout, in seconds. See timeout.
Set the protocol. See protocol.
Set the argument of the SMTP EHLO (or LMTP LHLO) command, and the domain part for the Message-ID header. See domain.
Enable or disable authentication and optionally choose the method. See auth.
Set or unset the user name for authentication. See user.
Evaluate password for authentication. See passwordeval.
Enable or disable TLS/SSL. See tls.
Enable or disable STARTTLS for TLS. See tls_starttls.
Set or unset a trust file for TLS. See tls_trust_file.
Deprecated. Set or unset a certificate revocation list (CRL) file for TLS. See tls_crl_file.
Set ot unset the fingerprint of a trusted TLS certificate. See tls_fingerprint.
Set or unset a key file for TLS. See tls_key_file.
Set or unset a cert file for TLS. See tls_cert_file.
Enable or disable server certificate checks for TLS. See tls_certcheck.
Set or unset TLS priorities. See tls_priorities.
Set or unset override for TLS host verification. See tls_host_override.
Deprecated, use ‘--tls-priorities’ instead. Set or unset minimum bit size of the Diffie-Hellman (DH) prime. See tls_min_dh_prime_bits.
Set the envelope-from address. See from and allow_from_override.
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. See Choosing an account.
Set or unset DSN notification conditions. See dsn_notify.
Set or unset the DSN notification amount. See dsn_return. Note that ‘hdrs’ is accepted as an alias for ‘headers’ to be compatible with sendmail.
Set From header handling. See set_from_header.
Set Date header handling. See set_date_header.
Set Message-ID header handling. See set_msgid_header.
Enable or disable the removal of Bcc headers. See remove_bcc_headers.
Enable or disable the replacement of To/Cc/Bcc with "To: undisclosed-recipients:;". See undisclosed_recipients.
Set or unset the log file. See logfile.
Set or unset the log file time format. See logfile_time_format.
Enable or disable syslog logging. See syslog.
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 the envelope from address from the From header of the mail.
Set or unset an aliases file. See aliases.
Set a full name to be used in a From header if msmtp adds one. See from_full_name.
Obsolete. See auto_from.
Obsolete. See maildomain.
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: ‘-Amode’, ‘-Btype’, ‘-bm’, ‘-G’, ‘-hN’, ‘-i’, ‘-L tag’, ‘-m’, ‘-n’, ‘-O option=value’, ‘-ox value’
There are three ways to choose the account to use.
If none of the above options is used (or if no account has a matching from command), then the account "default" is used.
SYSCONFDIR/msmtprc’The system configuration file. Use the --version option to find out what
SYSCONFDIR is on your platform.
~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config.’The default user configuration file.
~/.netrc and SYSCONFDIR/netrc’The netrc file contains login information. Before prompting for a
password, msmtp will search it in ~/.netrc and SYSCONFDIR/netrc.
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 used to buffer the headers of the mail but not the mail body, so the file will not 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).
Transport Layer Security (TLS) "… 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" (quote from RFC2246).
A server can use TLS in one of two modes:
The first mode is the default, but you can switch to the second mode by disabling tls_starttls.
When TLS is started, the server sends a certificate to identify itself. To verify the server identity, a client program is expected to check that the certificate is formally correct and that it was issued by a Certificate Authority (CA) that the user trusts. (There can also be certificate chains with intermediate CAs.)
The list of trusted CAs is specified using the tls_trust_file command. The default value ist ‘system’ and chooses the system-wide default, but you can also choose the trusted CAs yourself.
A fundamental problem with this is that you need to trust CAs. Like any other organization, a CA can be incompetent, malicious, subverted by bad people, or forced by government agencies to compromise end users without telling them. All of these things happened and continue to happen worldwide. The idea to have central organizations that have to be trusted for your communication to be secure is fundamentally broken.
Instead of putting trust in a CA, you can choose to trust only a single certificate for the server you want to connect to. For that purpose, specify the certificate fingerprint with tls_fingerprint. This makes sure that no man-in-the-middle can fake the identity of the server by presenting you a fraudulent certificate issued by some CA that happens to be in your trust list. However, you have to update the fingerprint whenever the server certificate changes, and you have to make sure that the change is legitimate each time, e.g. when the old certificate expired. This is inconvenient, but it’s the price to pay.
Information about a server certificate can be obtained with ‘--serverinfo --tls --tls-certcheck=off’. This includes the issuer CA of the certificate (so you can trust that CA via ‘tls_trust_file’), and the fingerprint of the certificate (so you can trust that particular certificate via ‘tls_fingerprint’). See Server information mode.
If you need to fine tune TLS parameters, have a look at the tls_priorities command.
TLS also allows the server to verify the identity of the client. For this purpose, the client has to present a certificate issued by a CA that the server trusts. To present that certificate, the client also needs the matching key file. You can set the certificate and key files using tls_cert_file and tls_key_file. This mechanism can also be used to authenticate users, so that traditional user / password authentication is not necessary anymore. See the EXTERNAL mechanism in Authentication.
# Enable TLS tls on # Enable TLS client certificates tls_cert_file /path/to/client_cert tls_key_file /path/to/client_key # Enable authentication via the EXTERNAL mechanism (optional; depends on server) # The user name is empty because the server should get it from the client cert auth external user ""
You can also use client certificates stored on some external authentication
device by specifying GnuTLS device URIs in tls_cert_file and
tls_key_file. You can find the correct URIs using p11tool
--list-privkeys --login (p11tool is bundled with GnuTLS). If your device
requires a PIN to access the data, you can specify that using one of the
password mechanisms (e.g. passwordeval, password).
tls_cert_file pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;serial=00000000;token=PIV_II%20%28PIV%20Card%20Holder%20pin%29;id=%01;object=Certificate%20for%20PIV%20Authentication;type=cert tls_key_file pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;serial=00000000;token=PIV_II%20%28PIV%20Card%20Holder%20pin%29;id=%01;object=PIV%20AUTH%20key;type=private passwordeval gpg2 --no-tty -q -d ~/.smart-card-pin.gpg
Many SMTP servers require a client to authenticate before sending mail.
Usually a user name and a password are used for authentication. The user name specified in the configuration file with the user command. There are five different methods to specify the password:
$ secret-tool store --label=msmtp \ host mail.freemail.example \ service smtp \ user joe.smith
On Mac OS X, use the following command:
security add-internet-password -s mail.freemail.example -r smtp -a joe.smith -w
In both examples, replace mail.freemail.example with the SMTP server name, and joe.smith with your user name.
It is recommended to use method 1 or 2.
Multiple authentication methods exist. Most servers support only some of them. Historically, sophisticated methods were developed to protect passwords from being sent unencrypted to the server, but nowadays everybody needs Transport Layer Security anyway, so the simple methods suffice since the whole session is protected. A suitable authentication method is chosen automatically, and when TLS is disabled for some reason, only methods that avoid sending cleartext passwords are considered.
The following user / password methods are supported:
There are currently three authentication methods that are not based on user / password information and have to be chosen manually:
It depends on the underlying authentication library and its version whether a particular method is supported or not. Use --version to find out which methods are supported by your version.
In situations such as delivery failure or delay, the mail system usually generates a message for the sender of the mail, 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. See 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 and --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 and --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.
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 are set with the from command or --from option. The latter can be disabled with the allow_from_override command.
When logging is enabled, msmtp will generate one log line for each mail it tries to send.
The line will include the following information:
host=hostname
tls=(on|off)
auth=(on|off)
user=name
from=address
recipients=addr1,addr2,…
mailsize=number
smtpstatus=number,
smtpmsg='message'. Multiline SMTP messages will be concatenated into one
line.
errormsg='message'
sysexits.h; ‘EX_OK’ indicates
success): exitcode=EX_…
If a logfile is given with the logfile command, this log line will be prepended with the current date and time (formatted according to logfile_time_format) and appended to the specified file.
If syslog logging is enabled with the syslog command, the log line is passed to the syslog service with the specified facility.
Msmtp transmits mails unaltered to the SMTP server, with the following exceptions:
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:
If TLS is activated for server information mode, the following information will be printed about the SMTP server’s TLS certificate (if available):
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. Destinations defined in RFC 1985 are:
# Example for a user configuration file ~/.msmtprc # # This file focusses on TLS and authentication. Features not used here include # logging, timeouts, SOCKS proxies, TLS parameters, Delivery Status Notification # (DSN) settings, and more. # Set default values for all following accounts. defaults # Use the mail submission port 587 instead of the SMTP port 25. port 587 # Always use TLS. tls on # Set a list of trusted CAs for TLS. The default is to use system settings, but # you can select your own file. #tls_trust_file /etc/ssl/certs/ca-certificates.crt # A freemail service account freemail # Host name of the SMTP server host smtp.freemail.example # As an alternative to tls_trust_file, you can use tls_fingerprint # to pin a single certificate. You have to update the fingerprint when the # server certificate changes, but an attacker cannot trick you into accepting # a fraudulent certificate. Get the fingerprint with # $ msmtp --serverinfo --tls --tls-certcheck=off --host=smtp.freemail.example #tls_fingerprint 00:11:22:33:44:55:66:77:88:99:AA:BB:CC:DD:EE:FF:00:11:22:33 # Envelope-from address from joe_smith@freemail.example # Authentication. The password is given using one of five methods, see below. auth on user joe.smith # Password method 1: Add the password to the system keyring, and let msmtp get # it automatically. To set the keyring password using Gnome's libsecret: # $ secret-tool store --label=msmtp \ # host smtp.freemail.example \ # service smtp \ # user joe.smith # Password method 2: Store the password in an encrypted file, and tell msmtp # which command to use to decrypt it. This is usually used with GnuPG, as in # this example. Usually gpg-agent will ask once for the decryption password. passwordeval gpg2 --no-tty -q -d ~/.msmtp-password.gpg # Password method 3: Store the password directly in this file. Usually it is not # a good idea to store passwords in cleartext files. If you do it anyway, at # least make sure that this file can only be read by yourself. #password secret123 # Password method 4: Store the password in ~/.netrc. This method is probably not # relevant anymore. # Password method 5: Do not specify a password. Msmtp will then prompt you for # it. This means you need to be able to type into a terminal when msmtp runs. # A second mail address at the same freemail service account freemail2 : freemail from joey@freemail.example # The SMTP server of your ISP account isp host mail.isp.example from smithjoe@isp.example auth on user 12345 # Set a default account account default : freemail
# A system wide configuration file 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 mail.oursite.example # Use TLS on port 465 port 465 tls on tls_starttls off # Construct envelope-from addresses of the form "user@oursite.example" from %U@oursite.example # Syslog logging with facility LOG_MAIL instead of the default LOG_USER syslog LOG_MAIL
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"
See 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
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.
Use the following settings:
proxy_host 127.0.0.1 proxy_port 9050 tls on
Use an IP address as proxy host name, so that msmtp does not leak a DNS query
when resolving it.
TLS is required to prevent exit hosts from reading your SMTP session. You also
need tls_trust_file or tls_fingerprint to check the server
identity.
Do not set ‘domain’ to something that you do not want to reveal (do not set
it at all if possible).
# 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
Msmtpd is a minimal SMTP server that pipes mails to msmtp (or some other program) for delivery. It can be used with system services that expect an SMTP server on the local host (see Example: using msmtpd as a system service), or it can be used by end users as a way to handle outgoing mail via msmtp with mail clients that insist on using SMTP (see Example: using msmtpd to handle outgoing mail for an SMTP-based mail client).
Msmtpd listens on 127.0.0.1 port 25 by default, but can also run without its own network sockets in inetd mode, where it handles a single SMTP session on standard input / output.
In the string that defines the command that msmtpd pipes each mail to, the first occurrence of ‘%F’ will be replaced with the envelope from address. Furthermore, all recipients of the mail will be appended as arguments. The command must not write to standard output, as that would mess up the SMTP session.
If the command that the mail is piped to reports an error, this is typically reported as a permanent failure by msmtpd (SMTP server return code 554). The command can optionally signal temporary errors by using return codes defined in ‘sysexits.h’, e.g. 75 for ‘EX_TEMPFAIL’. These will then be reported as temporary failures by msmtpd (SMTP server return code 451), which means the client should try again later.
To prevent abuse, msmtpd will allow only a limited number of concurrent SMTP sessions, and if authentication is active and an authentication failure occurrs, future authentication requests in any SMTP session will (for a limited duration) only be answered after a small delay.
Msmtpd handles the following options:
Print version information
Print help.
Start single SMTP session on stdin/stdout
Listen on the given IPv6 or IPv4 address instead of 127.0.0.1
Listen on the given port number instead of 25
Set logging: none (default), syslog, or logging to the given file.
Pipe mails to cmd instead of msmtp. Make sure to end this command with ‘--’ to separate options from arguments.
Require authentication with this user name. The password will be retrieved from the given passwordeval command (this works just like passwordeval in msmtp) or, if none is given, from the key ring or, if that fails, from a prompt.
Only use a local interface to listen on. Run msmtpd with correct user rights and permissions (e.g. use ‘CAP_NET_BIND_SERVICE’ to bind to port 25 instead of running as root, or use systemd with inetd service capabilities). Be aware that the pipe command will be run as the same user that msmtpd runs as. Enable logging to syslog with ‘--log=syslog’.
Example for managing msmtpd with ‘start-stop-daemon’:
# start msmtpd start-stop-daemon --start --pidfile /var/run/msmtpd.pid --make-pidfile --chuid msmtpd --background --exec /usr/local/bin/msmtpd -- --command '/usr/local/bin/msmtp -f %F --' # stop msmtpd start-stop-daemon --stop --pidfile /var/run/msmtpd.pid --remove-pidfile --quiet --signal TERM
Some mail clients cannot send outgoing mail with a program like msmtp and instead insist on using an SMTP server. You can configure msmtpd to be that SMTP server and hand your outgoing mail over to msmtp.
(Similarly, some mail clients cannot get incoming mail from a local mailbox and insist on using a POP3 or IMAP server. You can configure mpopd to be that POP3 server and serve incoming mail from a local mailbox. See the corresponding section in the mpop manual.)
For this purpose, msmtpd should listen on an unprivileged port, e.g. 2500. Furthermore, msmtpd should require authentication because otherwise anyone connecting to it can send mail using your account, even if it’s just other users or processes on your local machine.
Let’s use the user name msmtpd-user for this purpose. You have two options to manage the password:
secret-tool store --label=msmtpd host localhost service smtp user msmtpd-user
In this case, use the msmtpd option ‘--auth=msmtpd-user’.
msmtpd ... --auth=msmtpd-user,'gpg -q -d ~/.msmtpd-password.gpg'
The complete command then is (using the keyring):
msmtpd --port=2500 --auth=msmtpd-user --command='/path/to/your/msmtp -f %F --'
The mail client software must then be configured to use ‘localhost’ at port ‘2500’ for outgoing mail via SMTP, and to use authentication with user ‘msmtpd-user’ and the password you chose. The mail client will probably complain that the SMTP server does not support TLS, but in this special case that is ok since all communication between your mail client and msmtpd will stay on the local machine.
This setup also works with multiple mail accounts. Msmtp will pick the correct one based on the envelope-from address given to it via ‘-f %F’. You do not need multiple instances of msmtpd for this purpose, and therefore you need only one SMTP server in your mail client configuration.