2.3.1 Mailing the cronjob output

The default behavior is to mail the cronjob output to the user on whose behalf the cronjob is run. The message From: header is constructed as follows:

From: (Cron daemon) <owner@host>

where owner is the login name of the job owner, and host is the name of the host where it was run.

The Subject: header contains the owner login name, hostname of the server where the command was run and the command itself, in the following format:

Cron <user@host> command

A copy of execution environment is included in the message in the form of additional X-Cron-Env: headers, each containing a single environment variable.

The recipient of the message can be altered by setting the MAILTO, _JOB_MAILTO, and _MICRON_MAILTO variables in the crontab.

The MAILTO variable is the traditional way of defining the recipients for the job output. It affects all cronjobs in crontab that appear after it, until next definition of any of the three variables discussed, or end of the crontab file, whichever occurs first. It is also reflected in the environment of the job itself. See MAILTO.

If MAILTO is unset, the default behavior (mailing to the owner) is restored. If it is set to an empty string, cronjob output is discarded.

Notice the difference:

MAILTO =

Restores default behavior.

MAILTO = ""

Discards the output.

The two built-in variables _JOB_MAILTO and _MICRON_MAILTO behave as MAILTO, with the following differences:

The _JOB_MAILTO variable, if set, affects only the cronjob that immediately follows it. It is not reflected in the environment. See _JOB_MAILTO.

The _MICRON_MAILTO variable is rarely used. It works exactly as MAILTO, except that the actual value of the latter remains unchanged. It is not reflected in the environment, either.