How to calm the mail server?

Question

linux

The queue of letters accumulates all the time. I looked at the logs, every 10 minutes, 3 letters. I have 3 jobs in my cron every 10 minutes (php scripts), but there is not a single mention of mail in these scripts. In the panel itself, email notifications are disabled.

The graph shows when it drops to zero - I'm cleaning the message queue.
Here is the schedule for today

Answer 1

If jobs in the cron output something to the console (stdout, stderr), then the result is sent by mail to the user on whose behalf the job is run.
You can turn it off by adding MAILTO= to the beginning of the crontab, but it's better to figure out what the scripts output.