msmtp

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msmtp is a very simple and easy to use smtp client with excellent sendmail compatibility.

Installing

msmtp can be installed with package msmtp, available in the official repositories. Optionally, installing msmtp-mta creates a sendmail alias to msmtp.

Quick start

The following is an example of a msmtp configuration file for several accounts. If msmtp throws errors when using this file, search for double byte '\xc2\xa0' characters that may have been erroneously inserted.

~/.msmtprc
# Accounts will inherit settings from this section
defaults
auth             on
tls              on
tls_trust_file   /usr/share/ca-certificates/mozilla/Thawte_Premium_Server_CA.crt

# A first gmail address
account        gmail
host           smtp.gmail.com
port           587
from           username@gmail.com
user           username@gmail.com
password       password
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# A second gmail address
account    gmail2 : gmail
from       username2@gmail.com
user       username2@gmail.com
password   password2

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

# A provider's service
account   provider
host      smtp.provider.example

# Set a default account
account default : gmail

msmtp will refuse to start if user configuration file is readable and writeable to anyone else but the owner:

$ chmod 600 ~/.msmtprc

This does not apply to system configuration file (in Arch, this is /etc/msmtprc; copy the example over from /usr/share/doc/msmtp/ ).

Using the mail command

To send mails using the 'mail' command you must have the package s-nail installed.

Either install msmtp-mta or edit /etc/mail.rc to set sendmail

/etc/mail.rc
set sendmail=/usr/bin/msmtp

You need to have a .msmtprc file in the home of every users who want to send mail (for example if you want to send mails as root), or alternatively you can use a system wide /etc/msmtprc

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

/etc/msmtprc
aliases               /etc/aliases

and create an aliases file in /etc

/etc/aliases
# 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

Test msmtp

The -a flag specifies the account to use as sender; <username>@domain.com is the recipient.

Save (with the addresses you want to use)

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

Yadda, yadda, yadda.

as, say, "test.mail".

Then execute

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

Do not merely use "echo 'Yadda, yadda, yadda.'" instead of "cat test.mail". This causes at least Gmail and Yahoo to deliver the mail incorrectly.

Configuring cron for msmtp

Assuming you're using the default cron daemon, cronie, you'll want to make sure it knows to use msmtp rather than sendmail.

You can do this by either installing msmtp-mta or by editing the cronie.service 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 add this line to /etc/msmtprc:
    aliases /etc/aliases
    and create /etc/aliases:
    your_username: email@address.com
    — OR —
  • Add a MAILTO line to your crontab:
    MAILTO=email@address.com

Miscellaneous

Practical password management

The password directive may be omitted. In that case, if the account in question has auth set to a legitimate value other than off, 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. There is a solution for such cases: the --passwordeval parameter. You can call msmtp to use an external keyring tool like gpg:

msmtp --passwordeval 'gpg -d mypwfile.gpg'

If gpg prompt for the passphrase cannot be issued (e.g. when called from Mutt) then start the gpg-agent before.

A simple hack to start the agent is to execute a external command in your muttrc.

Note: Mutt uses the backtick ` command ` syntax to execute external commands

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.

Note: If you do this, you will have to restart mutt after gpg-agent clears the password to start sending emails again

If you cannot use a keyring tool for any reason, you may want to use the password directly. There is a patched version msmtp-pwpatchedAUR in the AUR that provides the --password parameter. Note that it is a huge security flaw, since any user connected to you machine can see the parameter of any command (in the /proc filesystem for example).

If this is not desired, an alternative is to place passwords in ~/.netrc, a file that can act as a common pool for msmtp, OfflineIMAP, and associated tools.

Using msmtp offline

Although msmtp is great, it requires that you be online to use it. This isn't 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 /usr/share/doc/msmtp/msmtpqueue. You might want to copy the scripts to a convenient location on your computer, (/usr/local/bin 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 QUEUEDIR=$HOME/.msmtpqueue line in the scripts (or delete the line, and export the QUEUEDIR variable in .bash_profile like so: export QUEUEDIR="$XDG_DATA_HOME/msmtpqueue").

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

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

Adding /usr/local/bin to your PATH can save you some keystrokes if you're 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 a msmtprc highlighting script for Vim. Install it from ./scripts/vim/msmtp.vim.

Send mail with PHP using msmtp

Look for sendmail_path option in your php.ini 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's readable by whatever you're 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's 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("your@email.com", "Test email from PHP", "msmtp as sendmail for PHP");
?>

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 /usr/share/ca-certificates/ 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 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

Server sent empty reply

If you get a "server sent empty reply" error, add the following line to ~/.msmtprc:

tls_starttls off