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Setting up msmtp

For a long time I struggled with setting up cronjobs properly. It always took a lot of trial and error. Most of the times this was due to an environment problem (or a typo). You could test your cronjob using a script or saving the command output to a file but it is still cumbersome. At the same time, it would also be nice to be notified whenever something goes wrong, such as your backup script failing all of a sudden.

In this post I explain how to set up msmtp so that your system will send you emails.

I had actually seen this output in syslog journalctl before but never really cared much about it:

(CRON) info (No MTA installed, discarding output)

cron sends an email whenever a cronjob has an output (unless of course it cannot send the email).

So I set up msmtp on my server(s).

Below you can find how I set it up (derived from these instructions):

  1. Install msmtp:

    sudo apt update && sudo apt install msmtp

  2. Decide whether you want to set this up system-wide or for a specific user.

    • For the system, create the config file msmtprc in /etc, for the user, create .msmtprc in the user's home directory.

  3. Decide how to provide the email password.

    At the end, I resorted to storing the password in plaintext in the config file. Here is why:

    msmtp recommends one of two methods to store the password: Using an encrypted password file or using the system keyring.

    • system keyring: The msmtp user example provides a usage example. I tried to use it by installing gnome-keyring but kept getting errors when using secret-tool store. My research indicates that this is due to running in headless mode. So this does not seem to work.

    • encrypted password file: I tried to use gpg for password management. However, gpg encrypted passwords can not be decrypted with cron/sendmail.

    If you can, use a dedicated email account for this purpose and ensure that only trusted users can access the config file.

  4. Set chmod for the configuration file(s) to 0600, otherwise msmtp will complain (sendmail: /home/<user>/.msmtprc: contains secrets and therefore must have no more than user read/write permissions)

    Examples provided by msmtp

    You can find system and user examples provided by msmtp in /usr/share/doc/msmtp/examples/.

  5. For cron to know where to send email to you need to do one of the following:

    1. specify an aliases file with a default email in /etc/aliases
    2. specify MAILTO=recipient@domain.tld in the crontab

  6. Finally, cron uses sendmail to send out emails. For current versions of msmtp (v1.8.8+) install msmtp-mta and set the set_from_header configuration setting to on.

    sudo apt update && sudo apt install msmtp-mta

    The from address can be set using from and the name using from_full_name to customize the name display. In my tests with cron, setting from_full_name has no effect, it will remain as "CronDaemon". However, only when set_from_header is set to on. If set_from_header is not set, you get something like "root (Cron Daemon)".

    Sendmail with older msmtp versions

    For older versions, you could just install the msmtp-mta package. However, you then get a From header in the emails as "root (Cron Daemon) \<>". If you want to customize this, create a sendmail alias in /usr/sbin. This is especially handy if you set this up for several servers and want to see which server an email is coming from. Follow these instructions to properly set it up.

The system msmtp configuration then looks as follows:

/etc/msmtprc
# find out more about the configuration here: https://marlam.de/msmtp/msmtprc.txt
# Set default values for all following accounts.
defaults
auth           on
tls            on
tls_starttls   on
logfile        /var/log/msmtp
aliases        /etc/aliases
set_from_header on

# server
account        server
host           mail.domain.tld
port           587
from           server@domain.tld
from_full_name "cron (my cool server)"
user           server@domain.tld
password

# Set a default account
account default : server

Updates to this blog post

  • 09.02.2026: Improved wording and brought it up to date with latest version (based on Debian Trixie).