msmtp - Man Page

• Send an email using the default account configured in ~/.msmtprc: echo "Hello world" | msmtp to@example.org
• Send an email using a specific account configured in ~/.msmtprc: echo "Hello world" | msmtp --account=account_name to@example.org
• Send an email without a configured account. The password should be specified in the ~/.msmtprc file: echo "Hello world" | msmtp --host=localhost --port=999 --from=from@example.org to@example.org

tldr.sh

Sendmail mode (default):

msmtp [option...] [--] recipient...
msmtp [option...] -t [--] [recipient...]

Configuration mode:

msmtp --configure <mailaddress>

Server information mode:

msmtp [option...] --serverinfo

Remote Message Queue Starting mode:

msmtp [option...] --rmqs=host|@domain|#queue

In the default sendmail mode, msmtp reads a mail from standard input and sends it to an SMTP server for delivery.
In server information mode, msmtp prints information about an SMTP server.
In Remote Message Queue Starting mode, msmtp sends a Remote Message Queue Starting request for a host, domain, or queue to an SMTP server.

The standard sendmail exit status codes are used, as defined in sysexits.h.

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

General options

--version

Print version information, including information about the libraries used.

--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 your 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!

Changing the mode of operation

--configure=mailaddress

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.

-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).

--rmqs=(host|@domain|#queue)

Send a Remote Message Queue Starting request for the given host, domain, or queue to the SMTP server and exit.

Configuration options

-C, --file=filename

Use the given file instead of ~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config as the user configuration file.

-a, --account=account_name

Use the given account instead of the account named "default". The settings of this account may be changed with command line options. This option cannot be used together with the --host option.

--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.

--port=number

Set the port number to connect to. See the port command.

--source-ip=[IP]

Set or unset an IP address to bind the socket to. See the source_ip command.

--proxy-host=[IP|hostname]

Set or unset a SOCKS proxy to use. See the proxy_host command.

--proxy-port=[number]

Set or unset a port number for the proxy host. See the proxy_port command.

--socket=[socketname]

Set or unset a local unix domain socket name to connect to. See the socket command.

--timeout=(off|seconds)

Set or unset a network timeout, in seconds. See the timeout command.

--protocol=(smtp|lmtp)

Set the protocol. See the protocol command.

--domain=[string]

Set the argument of the SMTP EHLO (or LMTP LHLO) command, and the domain part for the Message-ID header. See the domain command.

--auth[=(on|off|method)]

Enable or disable authentication and optionally choose the method. See the auth command.

--user=[username]

Set or unset the user name for authentication. See the user command.

--passwordeval=[cmd]

Evaluate password for authentication. See the passwordeval command.

--tls[=(on|off)]

Enable or disable TLS/SSL. See the tls command.

--tls-starttls[=(on|off)]

Enable or disable STARTTLS for TLS. See the tls_starttls command.

--tls-trust-file=[file]

Set or unset a trust file for TLS. See the tls_trust_file command.

--tls-crl-file=[file]

Deprecated. Set or unset a certificate revocation list (CRL) file for TLS. See the tls_crl_file command.

--tls-fingerprint=[fingerprint]

Set or unset the fingerprint of a trusted TLS certificate. See the tls_fingerprint command.

--tls-key-file=[file]

Set or unset a key file for TLS. See the tls_key_file command.

--tls-cert-file=[file]

Set or unset a cert file for TLS. See the tls_cert_file command.

--tls-certcheck[=(on|off)]

Enable or disable server certificate checks for TLS. See the tls_certcheck command.

--tls-priorities=[priorities]

Set or unset TLS priorities. See the tls_priorities command.

--tls-host-override=[host]

Set or unset override for TLS host verification. See the tls_host_override command.

--tls-min-dh-prime-bits=[bits]

Deprecated, use --tls-priorities instead. Set or unset minimum bit size of the Diffie-Hellman (DH) prime. See the tls_min_dh_prime_bits command.

Options specific to sendmail mode

-f, --from=address

Set the envelope-from address.
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 the from and allow_from_override commands.

-N, --dsn-notify=(off|cond)

Set or unset DSN notification conditions. See the dsn_notify command.

-R, --dsn-return=(off|ret)

Set or unset the DSN notification amount. See the dsn_return command. Note that hdrs is accepted as an alias for headers to be compatible with sendmail.

--set-from-header[=(auto|on|off)]

Set From header handling. See the set_from_header command.

--set-date-header[=(auto|off)]

Set Date header handling. See the set_date_header command.

--set-msgid-header[=(auto|off)]

Set Message-ID header handling. See the set_msgid_header command.

--remove-bcc-headers[=(on|off)]

Enable or disable the removal of Bcc headers. See the remove_bcc_headers command.

--undisclosed-recipients[=(on|off)]

Enable or disable the replacement of To/Cc/Bcc with "To: undisclosed-recipients:;". See the undisclosed_recipients command.

-X, --logfile=[file]

Set or unset the log file. See the logfile command.

--logfile-time-format=[fmt]

Set or unset the log file time format. See the logfile_time_format command.

--syslog[=(on|off|facility)]

Enable or disable syslog logging. See the syslog command.

-t, --read-recipients

Read recipient addresses from 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.

--aliases=[file]

Set or unset an aliases file. See the aliases command.

-Fname

Set a full name to be used in a From header if msmtp adds one. See the from_full_name command.

--auto-from[=(on|off)]

Obsolete. See the auto_from command.

--maildomain=[domain]

Obsolete. See the maildomain command.

--

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

A suggestion for a suitable configuration file can be generated using the --configure option. 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.

The user can choose which account to use in one of three ways:

--account=id

Use the given account. Command line settings override configuration file settings.

--host=hostname

Use only the settings from the command line; do not use any configuration file data.

--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.
Subadresses are supported. For example, the envelope from address user+detail@example.com will match the account for user@example.com.
Furthermore, the envelope-from address of the account may be a wildcard pattern. See the from command.

If none of the above options is used (or if no account has a matching from command), then the account "default" is used.

Msmtp transmits mails unaltered to the SMTP server, with the following exceptions:
- The Bcc header(s) will be removed. This behavior can be changed with the remove_bcc_headers command and --remove-bcc-headers option.
- A From header will be added if the mail does not have one. This can be changed with the set_from_header command and --set-from-header option. The header will use the envelope from address and optionally a full name set with the -F option or from_full_name command.
- A Date header will be added if the mail does not have one. This can be changed with the set_date_header command and --set-date-header option.
- A Message-ID header will be added if the mail does not have one. This can be changed with the set_msgid_header command and --set-msgid-header option.
- When undisclosed_recipients is set, the original To, Cc, and Bcc headers are removed and replaced with "To: undisclosed-recipients:;".

Skip to the Examples section for a quick start.

If it exists and is readable, a system wide configuration file SYSCONFDIR/msmtprc will be loaded, where SYSCONFDIR depends on your platform. Use --version to find out which directory is used.
If it exists and is readable, a user configuration file will be loaded (~/.msmtprc will be tried first followed by $XDG_CONFIG_HOME/msmtp/config by default, but see --version). Accounts defined in the user configuration file override accounts from the system configuration file.
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 ("), for example if its first or last character is a blank.
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.

Skip to the Examples section for a quick start.

Commands are as follows:

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.
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.

eval cmd

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.

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 is 25 ("smtp"), unless TLS without STARTTLS is used, in which case it is 465 ("smtps").

source_ip [IP]

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.

proxy_host [IP|hostname]

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 hostname argument disables proxy usage. The supported SOCKS protocol version is 5. If you want to use this with Tor, see also "Using msmtp with Tor" below.

proxy_port [number]

Set the port number for the proxy host. An empty number argument resets this to the default port.

socket socketname

Set the file name of a unix domain socket to connect to. This overrides both host/port and proxy_host/proxy_port.

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.

protocol (smtp|lmtp)

Set the protocol to use. Currently only SMTP and LMTP are supported. SMTP is the default. See the port command above for default ports.

domain argument

Use this command to set the argument of the SMTP EHLO (or LMTP LHLO) command, and the domain part of Message-ID headers if msmtp generates them (see the set_msgid_header command).
The default value localhost is stupid but usually works for EHLO. However it does not make sense for Message-ID headers. See the set_msgid_header command 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).

auth [(on|off|method)]

Enable or disable authentication and optionally choose a method to use. The argument on chooses a method automatically.
Usually a user name and a password are used for authentication. The user name is specified in the configuration file with the user command. There are five different methods to specify the password:
1. Add the password to the system key ring. Currently supported key rings are the Gnome key ring and the Mac OS X Keychain. For the Gnome key ring, use the command secret-tool (part of Gnome's libsecret) to store passwords: 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.
2. Store the password in an encrypted files, and use passwordeval to specify a command to decrypt that file, e.g. using GnuPG. See Examples.
3. Store the password in the configuration file using the password command. (Usually it is not considered a good idea to store passwords in cleartext files. If you do it anyway, you must make sure that the file can only be read by yourself.)
4. Store the password in ~/.netrc. This method is probably obsolete.
5. Type the password into the terminal when it is required.
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 TLS 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: plain (a simple cleartext method, with base64 encoding, supported by almost all servers), scram-sha-1 (a method that avoids cleartext passwords), scram-sha-256 (same but with stronger hash), cram-md5 (an obsolete method that avoids cleartext passwords, but is not considered secure anymore), digest-md5 (an overcomplicated obsolete method that avoids cleartext passwords, but is not considered secure anymore), login (a non-standard cleartext method similar to but worse than the plain method), ntlm (an obscure non-standard method that is now considered broken; it sometimes requires a special domain parameter passed via ntlmdomain).
There are currently three authentication methods that are not based on user / password information and have to be chosen manually: oauthbearer or its predecessor xoauth2 (an OAuth2 token from the mail provider is used as the password. See the documentation of your mail provider for details on how to get this token. The passwordeval command can be used to pass the regularly changing tokens into msmtp from a script or an environment variable), external (the authentication happens outside of the protocol, typically by sending a TLS client certificate, and the method merely confirms that this authentication succeeded), and gssapi (the Kerberos framework takes care of secure authentication, only a user name is required).
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.

user login

Set the user name for authentication. An empty argument unsets the user name.

password secret

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.

passwordeval [cmd]

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.

ntlmdomain [domain]

Set a domain for the ntlm authentication method. This is obsolete.

tls [(on|off)]

Enable or disable TLS (also known as SSL) for secured connections.
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: via a STARTTLS command (the session starts with the normal protocol initialization, and TLS is then started using the protocol's STARTTLS command), or immediately (TLS is initialized before the normal protocol initialization; this requires a separate port). 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).
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 auth.
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_starttls [(on|off)]

Choose the TLS variant: start TLS from within the session (on, default), or tunnel the session through TLS (off).

tls_trust_file file

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.

tls_crl_file [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.

tls_fingerprint [fingerprint]

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.

tls_key_file file

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.

tls_cert_file file

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.

tls_certcheck [(on|off)]

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!

tls_priorities [priorities]

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".

tls_host_override [host]

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.

tls_min_dh_prime_bits [bits]

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.

from envelope_from

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 the allow_from_override command.
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.

from_full_name name

Set a full name to be used in a From header if msmtp adds one. See the set_from_header command.

allow_from_override (on|off)

By default, the --from option overrides the from command. Set to off to disable this.

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.

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.

set_from_header [(auto|on|off)]

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.

set_date_header [(auto|off)]

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.

set_msgid_header [(auto|off)]

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.

remove_bcc_headers [(on|off)]

This command controls whether to remove Bcc headers. The default is to remove them.

undisclosed_recipients [(on|off)]

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.

logfile [file]

An empty argument disables logging (this is the default).
When logging is enabled by choosing a log file, msmtp will append one line to the log file for each mail it tries to send via the account that this log file was chosen for.
The line will include the following information: date and time in the format specified by logfile_time_format, host name of the SMTP server, whether TLS was used, whether authentication was used, authentication user name (only if authentication is used), envelope-from address, recipient addresses, size of the mail as transferred to the server (only if the delivery succeeded), SMTP status code and SMTP error message (only in case of failure and only if available), error message (only in case of failure and only if available), exit code (from sysexits.h; EX_OK indicates success).
If the filename is a dash (-), msmtp prints the log line to the standard output.

logfile_time_format [fmt]

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").

syslog [(on|off|facility)]

Enable or disable syslog logging. The facility can be one of LOG_USER, LOG_MAIL, LOG_LOCAL0, ..., LOG_LOCAL7. The default is LOG_USER.
Each time msmtp tries to send a mail via the account that contains this syslog command, it will log one entry to the syslog service with the chosen facility.
The line will include the following information: host name of the SMTP server, whether TLS was used, whether authentication was used, envelope-from address, recipient addresses, size of the mail as transferred to the server (only if the delivery succeeded), SMTP status code and SMTP error message (only in case of failure and only if available), error message (only in case of failure and only if available), exit code (from sysexits.h; EX_OK indicates success).

aliases [file]

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.

auto_from [(on|off)]

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 the maildomain is empty, the envelope-from address will only consist of the user name and not have a domain part. When auto_from is disabled, the envelope-from address must be set explicitly.

maildomain [domain]

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. This is only used when auto_from is on. The domain may be empty.

Configuration file

# 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

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 (but note that you cannot set a password this way):
set sendmail="/path/to/msmtp --host=mailhub -f me@example.com --tls --tls-trust-file=trust.crt"

If you have multiple mail accounts in your msmtp configuration file and let Mutt use the -f option to choose the right 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"

Using msmtp with mail

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

Using msmtp with Tor

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.
Do not set domain to something that you do not want to reveal (do not set it at all if possible).

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

SYSCONFDIR/msmtprc

System configuration file. Use --version to find out what SYSCONFDIR is on your platform.

~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config

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 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).

msmtp was written by Martin Lambers <marlam@marlam.de>.
Other authors are listed in the AUTHORS file in the source distribution.

sendmail(8), netrc(5) or ftp(1)

aerc-accounts(5), configuration.nix(5), msmtpd(1), neomutt(1).