[camtarn]

"You'll probably want to keep cron. But if you don't, then you should stop and disable the service. Because otherwise when trying to remove it with apt remove cron it will try to install postfix!"

...wat?

Is that actually a thing?

[pjc50]

Dependencies in debian systems which rely on "virtual" functionality can often have surprising results. At a guess removing cron removes things which depend on it - perhaps one of those is Exim. Something else "requires" an MTA, so it installs postfix instead to fill the gap.

[ThatGeoGuy]

This would be apt. Apt requires an MTA because maintainer messages / change-lists are sent as mail to the root user.

[stevekemp]

Close. It is cron that requires a package which provides `mail-transport-agent`, because output from cronjobs is traditionally emailed to users.

You can see this via:

      apt-cache show cron|grep -i mail

Note that the `apt` package itself does not require a MTA.