msmtp

msmtp is a very simple and easy to use SMTP client with fairly complete sendmail compatibility.

Installation

Install the msmtp package. Additionally, install msmtp-mta, which creates a sendmail alias to msmtp.

Basic setup

Since msmtp version 1.8.6 you can place your user configuration either at ~/.msmtprc or $XDG_CONFIG_HOME/msmtp/config. The following is an example of a msmtp configuration (the file is based on the per-user example file located at /usr/share/doc/msmtp/msmtprc-user.example; the system configuration file belongs at /etc/msmtprc and its corresponding example file is located at /usr/share/doc/msmtp/msmtprc-system.example).

The user configuration file must be explicitly readable/writeable by its owner or msmtp will fail:

$ chmod 600 ~/.msmtprc

To avoid saving the password in plain text in the configuration file, use passwordeval to launch an external program, or see the #Password management section below. This example using Gnu PG is commonly used to perform decryption of a password:

echo -e "password\n" | gpg --encrypt -o .msmtp-gmail.gpg # enter id (email...)

~/.msmtprc

passwordeval    "gpg --quiet --for-your-eyes-only --no-tty --decrypt ~/.msmtp-gmail.gpg"

OAuth2 Setup

OAuth2 can be used to securely authenticate msmtp when basic username/password authentication is unsupported by the site configuration or otherwise undesirable.

mailctl

msmtp alone lacks the ability to renew or authorize OAuth2 credentials. A comprehensive solution is using the mailctl utility which provides IMAP/SMTP clients with renewal capabilities and authorization of OAuth2 credentials.

To use mailctl, install mailctl-bin^AUR and configure msmtp to use it:

   # account at Google with oauth2 access                                    
   account [e-mail]
   from [e-mail]
   user [e-mail]
   auth oauthbearer
   passwordeval mailctl access [e-mail]
   host smtp.gmail.com
   port 587
   tls on
   tls_trust_file /etc/ssl/certs/ca-certificates.crt

Access token renewal happens automatically in the background transparent to the user.

Wrapper on oauth2.py

This is a scripted method, using the msmtp setting oauthbearer for authentication.

Once you have your Gmail API setup, you can implement the wrapper script oauth2token (that employs ) or an adaptation of oauth2token (that employs pass).

An configuration would be adapted thus:

auth oauthbearer
...
passwordeval <call_to_wrapper_script>

If you comment out the last line, will request you for the token that provides you, which is normally valid for one hour.

OAuth2 hack

To use XOAUTH2 authentication with Gmail (see official information), you can install the package. The package does a small hack so that the plain authentication method will send the instead of the , effectively disabling plain authentication and enabling XOAUTH2. Your would be adapted as follows:

from your@gmail_login_email
tls on
tls_starttls on
tls_certcheck off
auth plain
user any_thing_here
passwordeval "get-gmail-token"

The script can be found from the source files of the msmtp-oauth2 package. See more information on getmail link about how this works. And see Gmail API quickstart for instruction on registering a Gmail APP and authorizing it to access emails.

Using the mail command

To send mails using the mail command you must install the package s-nail, which also provides the command. You will also need to provide a -compatible MTA, either by installing msmtp-mta (which symlinks to ) or by editing to set the sendmail path:

A file will need to be in the home of every user who wants to send mail or alternatively the system wide /etc/msmtprc can be used.

msmtp also understands aliases. Add the following line to the defaults section of msmtprc or your local configuration file:

and create an aliases file in

Test functionality

The account option () tells which account to use as sender:

$ echo "hello there username." | msmtp -a default [e-mail]

Or, send both a subject and a body:

$ printf "Subject: Test\n\nhello there username." | msmtp -a default [e-mail]

Or, with the addresses in a file:

To: ''username''@domain.com
From: ''username''@gmail.com
Subject: A test

Hello there.

$ cat test.mail | msmtp -a default <username>@domain.com

Cronie default email client

To make Cronie use msmtp rather than sendmail, make sure msmtp-mta is installed, or edit the systemd unit:

/etc/systemd/system/cronie.service.d/msmtp.conf

[Service]
ExecStart=
ExecStart=/usr/bin/crond -n -m '/usr/bin/msmtp -t'

Then you must tell cronie or msmtp what your email address is, either by:

1. Add to /etc/msmtprc: and create : — OR —.

• Add a line to the crontab:

Password management

Passwords for msmtp can be stored in plaintext, encrypted files, or a keyring.

GNOME Keyring

Storing passwords in GNOME Keyring is supported natively in msmtp. Setup the keyring as described on the linked wiki page and install . Then, store a password by running:

secret-tool store --label=msmtp host smtp.your.domain service smtp user yourusername

msmtp should now find the password automatically.

GnuPG

The password directive may be omitted. In that case, if the account in question has set to a legitimate value other than , invoking msmtp from an interactive shell will ask for the password before sending mail. msmtp will not prompt if it has been called by another type of application, such as Mutt. For such cases, the parameter can be used to call an external keyring tool like GnuPG.

To do this, set up GnuPG, including gpg-agent to avoid having to enter the password every time. Then, create an encrypted password file for msmtp, as follows. Create a secure directory with permissions located on a tmpfs to avoid writing the unencrypted password to the disk. In that directory create a plain text file with the mail account password. Then, encrypt the file with your private key:

$ gpg --default-recipient-self -e /path/to/plain/password

Remove the plain text file and move the encrypted file to the final location, e.g. . In ~/.msmtprc add:

Normally this is sufficient for a GUI password prompt to appear when, for example, sending a message from Mutt. If gpg prompt for the passphrase cannot be issued, then start the gpg-agent before. A simple hack to start the agent is to execute a external command in your muttrc using the backtick syntax. For example, you can put something like the following in your muttrc:

muttrc

set my_msmtp_pass=`gpg -d mypwfile.gpg`

Mutt will execute this when it starts, gpg-agent will cache your password, msmtp will be happy and you can send mail.

An alternative is to place passwords in ~/.netrc, a file that can act as a common pool for msmtp, OfflineIMAP, and associated tools.

pass

You may store your credentials inside of the pass password manager.

If you are using your main password (which is customarily stored in the first line of your pass file) to login into your SMTP server, you can add the following to your :

If you are using Gmail, and have set up an app password, the following configuration will suit you better. Save your app password inside your password file, but with a prefix:

Then add the following to your :

In either case, trying to send an email with msmtp will trigger , which may ask you for your master password if you have not entered it recently.

Miscellaneous

Using msmtp offline

Although msmtp is great, it requires that you be online to use it. This is not ideal for people on laptops with intermittent connections to the Internet or dialup users. Several scripts have been written to remedy this fact, collectively called msmtpqueue.

The scripts are installed under . You might want to copy the scripts to a convenient location on your computer, ( is a good choice).

Finally, change your MUA to use msmtp-enqueue.sh instead of msmtp when sending e-mail. By default, queued messages will be stored in ~/.msmtpqueue. To change this location, change the line in the scripts (or delete the line, and export the QUEUEDIR variable in .bash_profile like so: ).

When you want to send any mail that you have created and queued up run:

$ /usr/local/bin/msmtp-runqueue.sh

Adding to your PATH can save you some keystrokes if you are doing it manually. The README file that comes with the scripts has some handy information, reading it is recommended.

Vim syntax highlighting

The msmtp source distribution includes an syntax-highlighting script for Vim, which is available at . The filetype is not detected automatically. The easiest way to enable it is by adding a modeline at the top or bottom of the file(s), i.e.:

# vim:filetype=msmtp

Send mail with PHP using msmtp

Look for option in your and edit like this:

sendmail_path = "/usr/bin/msmtp -C /path/to/your/config -t"

Note that you can not use a user configuration file (ie: one under ~/) if you plan on using msmtp as a sendmail replacement with php or something similar. In that case just create /etc/msmtprc, and remove your user configuration (or not if you plan on using it for something else). Also make sure it is readable by whatever you are using it with (php, django, etc...).

From the msmtp manual: Accounts defined in the user configuration file override accounts from the system configuration file. The user configuration file must have no more permissions than user read/write

So it is impossible to have a conf file under ~/ and have it still be readable by the php user.

To test it place this file in your php enabled server or using php-cli.

<?php
mail("[e-mail]", "Test email from PHP", "msmtp as sendmail for PHP");
?>

will fail to send mails and logs the warning:  unless you set the permissions of your /etc/msmtprc to user read/write (600).

Troubleshooting

Issues with TLS

If you see the following message:

msmtp: TLS certificate verification failed: the certificate hasn't got a known issuer

It probably means your tls_trust_file is not right.

Just follow the fine manual. It explains you how to find out the server certificate issuer of a given smtp server. Then you can explore the directory to find out if by any chance, the certificate you need is there. If not, you will have to get the certificate on your own. If you are using your own certificate, you can make msmtp trust it by adding the following to your ~/.msmtprc:

tls_fingerprint <SHA1 (recommended) or MD5 fingerprint of the certificate>

If you are trying to send mail through Gmail and are receiving this error, have a look at this thread or just use the second Gmail example above.

If you are completely desperate, but are 100% sure you are communicating with the right server, you can always temporarily disable the cert check:

$ msmtp --tls-certcheck off

If you see the following message:

msmtp: TLS handshake failed: the operation timed out

You may be affected by this bug. Recompile with --with-ssl=openssl (msmtp is compiled with GnuTLS by default).

Server sent empty reply

If you get a "server sent empty reply" error, this probably means the mail server does not support STARTTLS over port 587, but requires TLS over port 465.

To let msmtp use TLS over port 465, add the following line to ~/.msmtprc:

tls_starttls off

Zoho SMTP server

It can also happen on Zoho SMTP servers when the mail has no blank line between mail headers and mail body (see Debian bug #917260). The solution to this is to add an extra space in between:

"test-header\n\ntest-body"

Issues with GSSAPI

If you get the following error

GNU SASL: GSSAPI error in client while negotiating security context in gss_init_sec_context() in SASL library.  This is most likely due insufficient credentials or malicious interactions.

Try changing your auth setting to plain, instead of gssapi in your .msmtprc file :

auth plain

Envelope not accepted

In the case of

msmtp: envelope from address mail@server not accepted by the server
msmtp: server message: 530 5.5.1 Authentication Required.
msmtp: could not send mail (account default from /etc/msmtprc)

Try enabling authentication with

auth on

or any other method.