oasis-root

msmtp.1 (42510B)

.\" -*-nroff-*-
.\"
.\" Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014,
.\" 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
.\" Martin Lambers
.\" Copyright (C) 2011
.\" Scott Shumate
.\"
.\" Permission is granted to copy, distribute and/or modify this document
.\" under the terms of the GNU Free Documentation License, Version 1.2 or
.\" any later version published by the Free Software Foundation; with no
.\" Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
.TH MSMTP 1 2022-06
.SH NAME
msmtp \- An SMTP client
.SH SYNOPSIS
.IP "Sendmail mode (default):"
.B msmtp
[option...] [\-\-] recipient...
.br
.B msmtp
[option...] \-t [\-\-] [recipient...]
.IP "Configuration mode:"
.B msmtp
\-\-configure <mailaddress>
.IP "Server information mode:"
.B msmtp
[option...] \-\-serverinfo
.IP "Remote Message Queue Starting mode:"
.B msmtp
[option...] \-\-rmqs=\fIhost\fP|\fI@domain\fP|\fI#queue\fP
.SH DESCRIPTION
In the default sendmail mode, msmtp reads a mail from standard input and sends
it to an SMTP server for delivery.
.br
In server information mode, msmtp prints information about an SMTP server.
.br
In Remote Message Queue Starting mode, msmtp sends a Remote Message Queue
Starting request for a host, domain, or queue to an SMTP server.
.SH EXIT STATUS
The standard sendmail exit status codes are used, as defined in sysexits.h.
.SH OPTIONS
Options override configuration file settings.
.br
They are compatible with sendmail where appropriate.
.IP "\fBGeneral options\fP"
.RS
.IP "\-\-version"
Print version information, including information about the libraries used.
.IP "\-\-help"
Print help.
.IP "\-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.
.IP "\-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!
.RE
.IP "\fBChanging the mode of operation\fP"
.RS
.IP "\-\-configure=\fImailaddress\fP"
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.
.IP "\-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).
.IP "\-\-rmqs=(\fIhost\fP|\fI@domain\fP|\fI#queue\fP)"
Send a Remote Message Queue Starting request for the given host, domain, or
queue to the SMTP server and exit.
.RE
.IP "\fBConfiguration options\fP"
.RS
.IP "\-C, \-\-file=\fIfilename\fP"
Use the given file instead of ~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config as
the user configuration file.
.IP "\-a, \-\-account=\fIaccount_name\fP"
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 \fB\-\-host\fP option.
.IP "\-\-host=\fIhostname\fP"
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
\fB\-\-account\fP option.
.IP "\-\-port=\fInumber\fP"
Set the port number to connect to. See the \fBport\fP command.
.IP "\-\-source\-ip=[\fIIP\fP]"
Set or unset an IP address to bind the socket to. See the \fBsource_ip\fP command.
.IP "\-\-proxy\-host=[\fIIP\fP|\fIhostname\fP]"
Set or unset a SOCKS proxy to use. See the \fBproxy_host\fP command.
.IP "\-\-proxy\-port=[\fInumber\fP]"
Set or unset a port number for the proxy host. See the \fBproxy_port\fP command.
.IP "\-\-socket=[\fIsocketname\fP]"
Set or unset a local unix domain socket name to connect to. See the \fBsocket\fP command.
.IP "\-\-timeout=(\fIoff\fP|\fIseconds\fP)"
Set or unset a network timeout, in seconds. See the \fBtimeout\fP command.
.IP "\-\-protocol=(\fIsmtp\fP|\fIlmtp\fP)
Set the protocol. See the \fBprotocol\fP command.
.IP "\-\-domain=[\fIstring\fP]"
Set the argument of the SMTP EHLO (or LMTP LHLO) command. See the \fBdomain\fP
command.
.IP "\-\-auth[=(\fIon\fP|\fIoff\fP|\fImethod\fP)]"
Enable or disable authentication and optionally choose the method.
See the \fBauth\fP command.
.IP "\-\-user=\fI[username]\fP"
Set or unset the user name for authentication. See the \fBuser\fP command.
.IP "\-\-passwordeval=[\fIcmd\fP]"
Evaluate password for authentication. See the \fBpasswordeval\fP command.
.IP "\-\-tls[=(\fIon\fP|\fIoff\fP)]"
Enable or disable TLS/SSL. See the \fBtls\fP command.
.IP "\-\-tls\-starttls[=(\fIon\fP|\fIoff\fP)]"
Enable or disable STARTTLS for TLS. See the \fBtls_starttls\fP command.
.IP "\-\-tls\-trust\-file=[\fIfile\fP]"
Set or unset a trust file for TLS. See the \fBtls_trust_file\fP command.
.IP "\-\-tls\-crl\-file=[\fIfile\fP]"
Deprecated. Set or unset a certificate revocation list (CRL) file for TLS. See the
\fBtls_crl_file\fP command.
.IP "\-\-tls\-fingerprint=[\fIfingerprint\fP]"
Set or unset the fingerprint of a trusted TLS certificate. See the
\fBtls_fingerprint\fP command.
.IP "\-\-tls\-key\-file=[\fIfile\fP]"
Set or unset a key file for TLS. See the \fBtls_key_file\fP command.
.IP "\-\-tls\-cert\-file=[\fIfile\fP]"
Set or unset a cert file for TLS. See the \fBtls_cert_file\fP command.
.IP "\-\-tls\-certcheck[=(\fIon\fP|\fIoff\fP)]"
Enable or disable server certificate checks for TLS. See the
\fBtls_certcheck\fP command.
.IP "\-\-tls\-priorities=[\fIpriorities\fP]"
Set or unset TLS priorities. See the \fBtls_priorities\fP command.
.IP "\-\-tls\-host\-override=[\fIhost\fP]"
Set or unset override for TLS host verification. See the \fBtls_host_override\fP command.
.IP "\-\-tls\-min\-dh\-prime\-bits=[\fIbits\fP]"
Deprecated, use \-\-tls\-priorities instead.
Set or unset minimum bit size of the Diffie-Hellman (DH) prime. See the
\fBtls_min_dh_prime_bits\fP command.
.RE
.IP "\fBOptions specific to sendmail mode\fP"
.RS
.IP "\-f, \-\-from=\fIaddress\fP"
Set the envelope-from address.
.br
If no account was chosen yet (with \fB\-\-account\fP or \fB\-\-host\fP), this
option will choose the first account that has the given envelope-from address
(set with the \fBfrom\fP command). If no such account is found, "default" is
used.
.br
See the \fBfrom\fP and \fBallow_from_override\fP commands.
.IP "\-N, \-\-dsn\-notify=(\fIoff\fP|\fIcond\fP)"
Set or unset DSN notification conditions. See the \fBdsn_notify\fP command.
.IP "\-R, \-\-dsn\-return=(\fIoff\fP|\fIret\fP)"
Set or unset the DSN notification amount. See the \fBdsn_return\fP command.
Note that \fIhdrs\fP is accepted as an alias for \fIheaders\fP to be
compatible with sendmail.
.IP "\-\-set\-from\-header[=(\fIauto\fP|\fIon\fP|\fIoff\fP)]"
Set From header handling. See the \fBset_from_header\fP command.
.IP "\-\-set\-date\-header[=(\fIauto\fP|\fIoff\fP)]"
Set Date header handling. See the \fBset_date_header\fP command.
.IP "\-\-set\-msgid\-header[=(\fIauto\fP|\fIoff\fP)]"
Set Message-ID header handling. See the \fBset_msgid_header\fP command.
.IP "\-\-remove\-bcc\-headers[=(\fIon\fP|\fIoff\fP)]"
Enable or disable the removal of Bcc headers. See the \fBremove_bcc_headers\fP
command.
.IP "\-\-undisclosed\-recipients[=(\fIon\fP|\fIoff\fP)]"
Enable or disable the replacement of To/Cc/Bcc with "To: undisclosed-recipients:;".
See the \fBundisclosed_recipients\fP command.
.IP "\-X, \-\-logfile=[\fIfile\fP]"
Set or unset the log file. See the \fBlogfile\fP command.
.IP "\-\-logfile\-time\-format=[\fIfmt\fP]"
Set or unset the log file time format. See the \fBlogfile_time_format\fP command.
.IP "\-\-syslog[=(\fIon\fP|\fIoff\fP|\fIfacility\fP)]"
Enable or disable syslog logging. See the \fBsyslog\fP command.
.IP "\-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.
.IP "\-\-read\-envelope\-from"
Read the envelope from address from the From header of the mail.
.IP "\-\-aliases=[\fIfile\fP]"
Set or unset an aliases file. See the \fBaliases\fP command.
.IP "\-F\fIname\fP"
Msmtp adds a From header to mails that lack it, using the envelope from
address. This option allows one to set a full name to be used in that header.
.IP "\-\-auto\-from[=(\fIon\fP|\fIoff\fP)]"
Obsolete. See the \fBauto_from\fP command.
.IP "\-\-maildomain=[\fIdomain\fP]"
Obsolete. See the \fBmaildomain\fP command.
.IP "\-\-"
This marks the end of options. All following arguments will be treated as
recipient addresses, even if they start with a `\-'.
.RE
.PP
The following options are accepted but ignored for sendmail compatibility:
.br
\-B\fItype\fP, \-bm, \-G, \-h\fIN\fP, \-i, \-L \fItag\fP, \-m,
\-n, \-O \fIoption=value\fP, \-o\fIx\fP \fIvalue\fP
.SH USAGE
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.
.br
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.
.PP
The user can choose which account to use in one of three ways:
.IP "\-\-account=\fIid\fP"
Use the given account. Command line settings override configuration file
settings.
.IP "\-\-host=\fIhostname\fP
Use only the settings from the command line; do not use any configuration file
data.
.IP "\-\-from=\fIaddress\fP 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 \fBfrom\fP command. This
works only when neither \fB\-\-account\fP nor \fB\-\-host\fP is used.
.br
Subadresses are supported. For example, the envelope from address
\fIuser+detail@example.com\fP will match the account for \fIuser@example.com\fP.
.br
Furthermore, the envelope-from address of the account may be a wildcard pattern.
See the \fBfrom\fP command.
.PP
If none of the above options is used (or if no account has a matching
\fBfrom\fP command), then the account "default" is used.
.PP
Msmtp transmits mails unaltered to the SMTP server, with the following exceptions:
.br
- The Bcc header(s) will be removed. This behavior can be changed with the
\fBremove_bcc_headers\fP command and \fB\-\-remove\-bcc\-headers\fP option.
.br
- A From header will be added if the mail does not have one. This can be changed
with the \fBset_from_header\fP command and \fB\-\-set\-from\-header\fP option.
The header will use the envelope from address and optionally a full name set
with the \fB\-F\fP option.
.br
- A Date header will be added if the mail does not have one. This can be changed
with the \fBset_date_header\fP command and \fB\-\-set\-date\-header\fP option.
.br
- A Message-ID header will be added if the mail does not have one. This can be changed
with the \fBset_msg_header\fP command and \fB\-\-set\-msgid\-header\fP option.
.br
- When \fBundisclosed_recipients\fP is set, the original To, Cc, and Bcc headers
are removed and replaced with "To: undisclosed-recipients:;".
.PP
Skip to the EXAMPLES section for a quick start.
.SH CONFIGURATION FILES
If it exists and is readable, a system wide configuration file
SYSCONFDIR/msmtprc will be loaded, where SYSCONFDIR depends on your platform.
Use \fB\-\-version\fP to find out which directory is used.
.br
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 \fB\-\-version\fP). Accounts defined in the user configuration
file override accounts from the system configuration file.
.br
Configuration data from either file can be changed by command line options.
.PP
A configuration file is a simple text file.  Empty lines and comment lines
(whose first non-blank character is `#') are ignored.
.br
Every other line must contain a command and may contain an argument to that
command.
.br
The argument may be enclosed in double quotes ("), for example if its first or
last character is a blank.
.br
If a file name starts with the tilde (~), this tilde will be replaced by $HOME.
If a command accepts the argument \fIon\fP, it also accepts an empty argument
and treats that as if it was \fIon\fP.
.br
Commands are organized in accounts. Each account starts with the \fBaccount\fP
command and defines the settings for one SMTP account.
.PP
Skip to the EXAMPLES section for a quick start.
.PP
Commands are as follows:
.IP "defaults"
Set defaults. The following configuration commands will set default values for
all following account definitions in the current configuration file.
.IP "account \fIname\fP [:\fIaccount\fP[,...]]"
Start a new account definition with the given name. The current default values
are filled in.
.br
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.
.IP "eval \fIcmd\fP"
Replace the current configuration file line with the first line of the output
(stdout) of the command \fIcmd\fP. This can be used to decrypt settings or to
create them via scripts. For example, \fIeval echo host localhost\fP replaces
the current line with \fIhost localhost\fP.
.br
The \fIcmd\fP command must not mess with standard input; if in doubt, append
\fI< /dev/null\fP.
.br
Note that for passwords you can also use the \fBpasswordeval\fP command instead
of \fIeval password cmd\fP. This has the advantage that the command is only
evaluated if needed.
.IP "host \fIhostname\fP"
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.
.IP "port \fInumber\fP"
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").
.IP "source_ip [\fIIP\fP]"
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.
.IP "proxy_host [\fIIP|hostname\fP]"
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 \fIhostname\fP 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.
.IP "proxy_port [\fInumber\fP]"
Set the port number for the proxy host. An empty \fInumber\fP argument resets
this to the default port.
.IP "socket \fIsocketname\fP"
Set the file name of a unix domain socket to connect to. This overrides
both \fBhost\fP/\fBport\fP and \fBproxy_host\fP/\fBproxy_port\fP.
.IP "timeout (\fIoff\fP|\fIseconds\fP)"
Set or unset a network timeout, in seconds. The argument \fIoff\fP means that no
timeout will be set, which means that the operating system default will be used.
.IP "protocol (\fIsmtp\fP|\fIlmtp\fP)"
Set the protocol to use. Currently only SMTP and LMTP are supported. SMTP is
the default. See the \fBport\fP command above for default ports.
.IP "domain \fIargument\fP"
Use this command to set the argument of the SMTP EHLO (or LMTP LHLO) command.
The default is \fIlocalhost\fP, 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).
.br
The following substitution patterns are supported:
.br
%H will be replaced by $HOSTNAME, or if that fails by the host name of the system.
.br
%C will be replaced by the canonical name of %H.
.br
%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).
.IP "auth [(\fIon\fP|\fIoff\fP|\fImethod\fP)]"
Enable or disable authentication and optionally choose a method to use. The
argument \fIon\fP chooses a method automatically.
.br
Usually a user name and a password are used for authentication. The user name
is specified in the configuration file with the \fBuser\fP command. There are five
different methods to specify the password:
.br
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.
.br
2. Store the password in an encrypted files, and use \fBpasswordeval\fP
to specify a command to decrypt that file, e.g. using GnuPG. See EXAMPLES.
.br
3. Store the password in the configuration file using the \fBpassword\fP 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.)
.br
4. Store the password in ~/.netrc. This method is probably obsolete.
.br
5. Type the password into the terminal when it is required.
.br
It is recommended to use method 1 or 2.
.br
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.
.br
The following user / password methods are supported: \fIplain\fP (a simple
cleartext method, with base64 encoding, supported by almost all servers),
\fIscram\-sha\-1\fP (a method that avoids cleartext passwords),
\fIscram\-sha\-256\fP (same but with stronger hash),
\fIcram\-md5\fP (an obsolete method that avoids cleartext passwords, but is not
considered secure anymore),
\fIdigest\-md5\fP (an overcomplicated
obsolete method that avoids cleartext passwords, but is not considered secure
anymore), \fIlogin\fP (a non-standard cleartext method similar to but worse
than the plain method), \fIntlm\fP (an obscure non-standard method that is now
considered broken; it sometimes requires a special domain parameter passed via
\fBntlmdomain\fP).
.br
There are currently three authentication methods that are not based on user /
password information and have to be chosen manually: \fIoauthbearer\fP or its
predecessor \fIxoauth2\fP (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 \fBpasswordeval\fP command can be used to pass the regularly changing
tokens into msmtp from a script or an environment variable),
\fIexternal\fP (the
authentication happens outside of the protocol, typically by sending a TLS
client certificate, and the method merely confirms that this authentication
succeeded), and \fIgssapi\fP (the Kerberos framework takes care of secure
authentication, only a user name is required).
.br
It depends on the underlying authentication library and its version whether a
particular method is supported or not. Use \fB\-\-version\fP to find out which
methods are supported.
.IP "user \fIlogin\fP"
Set the user name for authentication. An empty argument unsets the user name.
.IP "password \fIsecret\fP"
Set the password for authentication. An empty argument unsets the password.
Consider using the \fBpasswordeval\fP command or a key ring instead of this
command, to avoid storing cleartext passwords in the configuration file.
.IP "passwordeval [\fIcmd\fP]"
Set the password for authentication to the output (stdout) of the command
\fIcmd\fP.
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.
.br
The \fIcmd\fP command must not mess with standard input; if in doubt, append
\fI< /dev/null\fP.
.IP "ntlmdomain [\fIdomain\fP]"
Set a domain for the \fBntlm\fP authentication method. This is obsolete.
.IP "tls [(\fIon\fP|\fIoff\fP)]"
Enable or disable TLS (also known as SSL) for secured connections.
.br
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).
.br
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 \fBtls_starttls\fP.
.br
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.)
.br
The list of trusted CAs is specified using the \fBtls_trust_file\fP command.
The default value ist "system" and chooses the system-wide default, but you can
also choose the trusted CAs yourself.
.br
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.
.br
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 \fBtls_fingerprint\fP. 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.
.br
Information about a server certificate can be obtained with \fI\-\-serverinfo
\-\-tls \-\-tls\-certcheck=off\fP. This includes the issuer CA of the certificate (so
you can trust that CA via \fBtls_trust_file\fP), and the fingerprint of the
certificate (so you can trust that particular certificate via
\fBtls_fingerprint\fP).
.br
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 \fBtls_cert_file\fP and
\fBtls_key_file\fP. This mechanism can also be used to authenticate users, so
that traditional user / password authentication is not necessary anymore. See the
\fIexternal\fP mechanism in \fBauth\fP.
.br
You can also use client certificates stored on some external authentication
device by specifying GnuTLS device URIs in \fBtls_cert_file\fP and
\fBtls_key_file\fP. You can find the correct URIs using \fBp11tool
\-\-list-privkeys \-\-login\fP (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. \fBpasswordeval\fP, \fBpassword\fP). 
.IP "tls_starttls [(\fIon\fP|\fIoff\fP)]"
Choose the TLS variant: start TLS from within the session (\fIon\fP, default),
or tunnel the session through TLS (\fIoff\fP).
.IP "tls_trust_file \fIfile\fP"
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
\fBtls_crl_file\fP.
.IP "tls_crl_file [\fIfile\fP]"
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.
.IP "tls_fingerprint [\fIfingerprint\fP]"
Set the fingerprint of a single certificate to accept for TLS. This certificate
will be trusted regardless of its contents (this overrides \fBtls_trust_file\fP).
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 \fI\-\-serverinfo \-\-tls \-\-tls\-certcheck=off \-\-tls\-fingerprint=\fP
to get the server certificate fingerprint.
.IP "tls_key_file \fIfile\fP"
Send a client certificate to the server (use this together with
\fBtls_cert_file}\fP).
The file must contain the private key of a certificate in PEM format. An empty
argument disables this feature.
.IP "tls_cert_file \fIfile\fP"
Send a client certificate to the server (use this together with
\fBtls_key_file\fP).
The file must contain a certificate in PEM format. An empty argument disables
this feature.
.IP "tls_certcheck [(\fIon\fP|\fIoff\fP)]"
Enable or disable checks of the server certificate. They are enabled by default.
Disabling them will override \fBtls_trust_file\fP and \fBtls_fingerprint\fP.
WARNING: When the checks are disabled, TLS sessions will not be secure!
.IP "tls_priorities [\fIpriorities\fP]"
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
\fIpriorities\fP string depends on the TLS library. Use \fI\-\-version\fP to find out
which TLS library you use.
.br
For GnuTLS, see the section on Priority Strings in the manual.
.br
For libtls, the \fIpriorites\fP 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 \fItls_config_parse_protocols\fP, \fItls_config_set_ciphers\fP,
and \fItls_config_set_ecdhecurves\fP. Unrecognized parts of the \fIpriorities\fP string
will be ignored. Example: "PROTOCOLS=TLSv1.3 CIPHERS=ECDHE-RSA-AES128-SHA256 ECDHECURVES=P-384". 
.IP "tls_host_override [\fIhost\fP]"
By default, TLS host verification uses the host name given by the \fBhost\fP command.
This command allows one to use a different host name for verification. This is only
useful in special cases.
.IP "tls_min_dh_prime_bits [\fIbits\fP]"
Deprecated, use \fBtls_priorities\fP 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.
.IP "from \fIenvelope_from\fP"
Set the envelope-from address. The following substitution patterns are supported:
.br
%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.
.br
%H will be replaced by $HOSTNAME, or if that fails by the host name of the system.
.br
%C will be replaced by the canonical name of %H.
.br
%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).
.br
Note that the obsolete \fBauto_from\fP command replaces this envelope-from address.
.br
To enforce the use of this envelope-from address and ignore the \-f / \-\-from option,
see the \fBallow_from_override\fP command.
.br
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 \fI\-\-from\fP option to match a single account.
.IP "allow_from_override (\fIon\fP|\fIoff\fP)
By default, the \fI\-\-from\fP option overrides the \fBfrom\fP command.
Set to \fIoff\fP to disable this.
.IP "dsn_notify (\fIoff\fP|\fIcondition\fP)"
This command sets the condition(s) under which the mail system should send DSN
(Delivery Status Notification) messages. The argument \fIoff\fP disables
explicit DSN requests, which means the mail system decides when to send DSN
messages. This is the default.
The \fIcondition\fP must be \fInever\fP, to never request notification, or a
comma separated list (no spaces!) of one or more of the following:
\fIfailure\fP, to request notification on transmission failure, \fIdelay\fP, to
be notified of message delays, \fIsuccess\fP, to be notified of successful
transmission. The SMTP server must support the DSN extension.
.IP "dsn_return (\fIoff\fP|\fIamount\fP)"
This command controls how much of a mail should be returned in DSN (Delivery
Status Notification) messages. The argument \fIoff\fP 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 \fIamount\fP must be \fIheaders\fP, to just return the message headers, or
\fIfull\fP, to return the full mail.  The SMTP server must support the DSN
extension.
.IP "set_from_header [(\fIauto\fP|\fIon\fP|\fIoff\fP)]"
When to set a From header: \fIauto\fP adds a From header if the mail does not
have one (this is the default), \fIon\fP always sets a From header and overrides
any existing one, and \fIoff\fP never sets a From header.
.br
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 \fIon\fP.
.br
The From header is created based on the envelope-from address. Disable
\fBallow_from_override\fP to prevent programs from setting their own
envelope-from address.
.br
For compatibility with older versions, \fBadd_missing_from_header\fP [(\fIon\fP|\fIoff\fP)]
is still supported and corresponds to the \fIauto\fP and \fIoff\fP settings.
.IP "set_date_header [(\fIauto\fP|\fIoff\fP)]"
When to set a Date header: \fIauto\fP adds a Date header if the mail does not
have one (this is the default), and \fIoff\fP never sets a Date header.
.br
For compatibility with older versions, \fBadd_missing_date_header\fP [(\fIon\fP|\fIoff\fP)]
is still supported and corresponds to the \fIauto\fP and \fIoff\fP settings.
.IP "set_msgid_header [(\fIauto\fP|\fIoff\fP)]"
When to set a Message-ID header: \fIauto\fP adds a Message-ID header if the mail does not
have one (this is the default), and \fIoff\fP never sets a Message-ID header.
.IP "remove_bcc_headers [(\fIon\fP|\fIoff\fP)]"
This command controls whether to remove Bcc headers. The default is to remove them.
.IP "undisclosed_recipients [(\fIon\fP|\fIoff\fP)]"
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.
.IP "logfile [\fIfile\fP]"
An empty argument disables logging (this is the default).
.br
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.
.br
The line will include the following information: date and time in the format
specified by \fBlogfile_time_format\fP, 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).
.br
If the filename is a dash (\-), msmtp prints the log line to the standard
output.
.IP "logfile_time_format [\fIfmt\fP]"
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").
.IP "syslog [(\fIon\fP|\fIoff\fP|\fIfacility\fP)]"
Enable or disable syslog logging. The facility can be one of LOG_USER, LOG_MAIL,
LOG_LOCAL0, ..., LOG_LOCAL7. The default is LOG_USER.
.br
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.
.br
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).
.br
.IP "aliases [\fIfile\fP]"
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:
.br
    local: someone@example.com, person@domain.example
.br
Multiple replacement addresses are separated with commas.  Comments start with `#'
and continue to the end of the line.
.br
The local address \fIdefault\fP has special significance and is matched if the
local address is not found in the aliases file.  If no \fIdefault\fP alias is
found, then the local address is left as is.
.br
An empty argument to the aliases command disables the replacement of local
addresses.  This is the default.
.IP "auto_from [(\fIon\fP|\fIoff\fP)]
Obsolete; you can achieve the same and more using the substitution patterns of the
\fIfrom\fP command.
.br
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 \fBUSER\fP or, if that fails, to
\fBLOGNAME\fP or, if that fails, to the login name of the current user.  The
domain part can be set with the \fBmaildomain\fP 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.
.IP "maildomain [\fIdomain\fP]"
Obsolete; you can achieve the same and more using the substitution patterns of the
\fIfrom\fP command.
.br
Set a domain part for the generation of an envelope-from address. This is only
used when \fIauto_from\fP is on. The domain may be empty.
.br
.SH EXAMPLES
.br
.B Configuration file
.PP
.br
# Example for a user configuration file ~/.msmtprc
.br
#
.br
# This file focusses on TLS and authentication. Features not used here include
.br
# logging, timeouts, SOCKS proxies, TLS parameters, Delivery Status Notification
.br
# (DSN) settings, and more.
.br
.br
# Set default values for all following accounts.
.br
defaults
.br
.br
# Use the mail submission port 587 instead of the SMTP port 25.
.br
port 587
.br
.br
# Always use TLS.
.br
tls on
.br
.br
# Set a list of trusted CAs for TLS. The default is to use system settings, but
.br
# you can select your own file.
.br
#tls_trust_file /etc/ssl/certs/ca\-certificates.crt
.br
.br
# A freemail service
.br
account freemail
.br
.br
# Host name of the SMTP server
.br
host smtp.freemail.example
.br
.br
# As an alternative to tls_trust_file, you can use tls_fingerprint
.br
# to pin a single certificate. You have to update the fingerprint when the
.br
# server certificate changes, but an attacker cannot trick you into accepting
.br
# a fraudulent certificate. Get the fingerprint with
.br
# $ msmtp \-\-serverinfo \-\-tls \-\-tls\-certcheck=off \-\-host=smtp.freemail.example
.br
#tls_fingerprint 00\::11\::22\::33\::44\::55\::66\::77\::88\::99\::AA\::BB\::CC\::DD\::EE\::FF\::00\::11\::22\::33
.br
.br
# Envelope-from address
.br
from joe_smith@freemail.example
.br
.br
# Authentication. The password is given using one of five methods, see below.
.br
auth on
.br
user joe.smith
.br
.br
# Password method 1: Add the password to the system keyring, and let msmtp get
.br
# it automatically. To set the keyring password using Gnome's libsecret:
.br
# $ secret\-tool store \-\-label=msmtp \\
.br
#   host smtp.freemail.example \\
.br
#   service smtp \\
.br
#   user joe.smith
.br
.br
# Password method 2: Store the password in an encrypted file, and tell msmtp
.br
# which command to use to decrypt it. This is usually used with GnuPG, as in
.br
# this example. Usually gpg\-agent will ask once for the decryption password.
.br
passwordeval gpg2 \-\-no\-tty \-q \-d ~/.msmtp\-password.gpg
.br
.br
# Password method 3: Store the password directly in this file. Usually it is not
.br
# a good idea to store passwords in cleartext files. If you do it anyway, at
.br
# least make sure that this file can only be read by yourself.
.br
#password secret123
.br
.br
# Password method 4: Store the password in ~/.netrc. This method is probably not
.br
# relevant anymore.
.br
.br
# Password method 5: Do not specify a password. Msmtp will then prompt you for
.br
# it. This means you need to be able to type into a terminal when msmtp runs.
.br
.br
# A second mail address at the same freemail service
.br
account freemail2 : freemail
.br
from joey@freemail.example
.br
.br
# The SMTP server of your ISP
.br
account isp
.br
host mail.isp.example
.br
from smithjoe@isp.example
.br
auth on
.br
user 12345
.br
.br
# Set a default account
.br
account default : freemail
.br
.PP
.B Using msmtp with Mutt
.PP
Create a configuration file for msmtp and add the following lines to your
Mutt configuration file:
.br
.B set sendmail="/path/to/msmtp"
.br
.B set use_from=yes
.br
.B set realname="Your Name"
.br
.B set from=you@example.com
.br
.B set envelope_from=yes
.br
The envelope_from=yes option lets Mutt use the
.BR \-f
option of msmtp. Therefore msmtp chooses the first account that matches
the from address you@example.com.
.br
Alternatively, you can use the
.BR \-a
option:
.br
.B set sendmail="/path/to/msmtp \-a my\-account"
.br
Or set everything from the command line (but note that you cannot set a password
this way):
.br
.B set sendmail="/path/to/msmtp \-\-host=mailhub \-f me@example.com \-\-tls
.B \-\-tls\-trust\-file=trust.crt"
.PP
If you have multiple mail accounts in your msmtp configuration file
and let Mutt use the
.BR \-f
option to choose the right one, you can easily switch accounts in Mutt with
the following Mutt configuration lines:
.br
.B macro generic\ "<esc>1"\ ":set from=you@example.com"
.br
.B macro generic\ "<esc>2"\ ":set from=you@your\-employer.example"
.br
.B macro generic\ "<esc>3"\ ":set from=you@some\-other\-provider.example"
.PP
.B Using msmtp with mail
.PP
Define a default account, and put the following in your ~/.mailrc:
.br
.B set sendmail="/path/to/msmtp"
.PP
.B Using msmtp with Tor
.PP
Use the following settings:
.br
.B proxy_host 127.0.0.1
.br
.B proxy_port 9050
.br
.B tls on
.br
Use an IP address as proxy host name, so that msmtp does not leak a DNS query
when resolving it.
.br
TLS is required to prevent exit hosts from reading your SMTP session.
.br
Do not set \fBdomain\fP to something that you do not want to reveal (do not set
it at all if possible).
.PP
.B Aliases file
.PP
# Example aliases file
# Send root to Joe and Jane
.br
root: joe_smith@example.com, jane_chang@example.com
# Send cron to Mark
.br
cron: mark_jones@example.com
# Send everything else to admin
.br
default: admin@domain.example
.SH FILES
.IP "SYSCONFDIR/msmtprc"
System configuration file. Use
.B \-\-version
to find out what SYSCONFDIR is on your platform.
.IP "~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config"
User configuration file.
.IP "~/.netrc and SYSCONFDIR/netrc"
The netrc file contains login information. Before prompting for a password,
msmtp will search it in ~/.netrc and SYSCONFDIR/netrc.
.SH ENVIRONMENT
.IP "USER, LOGNAME"
These variables override the user's login name when constructing an
envelope-from address. LOGNAME is only used if USER is unset.
.IP "TMPDIR"
Directory to create temporary files in. If this is unset, a system specific
default directory is used.
.br
A temporary file is only created when the
.BR \-t/\-\-read\-recipients
or
.BR \-\-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).
.IP "EMAIL, SMTPSERVER"
These environment variables are used only if neither \fB\-\-host\fP nor
\fB\-\-account\fP 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
\fB\-\-from\fP or \fB\-\-read\-envelope\-from\fP. Currently SMTPSERVER must
contain a plain host name (no URL), and EMAIL must contain a plain address (no
names or additional information).
.SH AUTHORS
msmtp was written by Martin Lambers <marlam@marlam.de>.
.br
Other authors are listed in the AUTHORS file in the source distribution.
.SH SEE ALSO
.BR sendmail (8),
.BR netrc (5)
or
.BR ftp (1)