fix(postfix): Fix broken relay access

Currently for some reason postfix decided to drop all email that are
supposed to be relayed by default. This is obviously unwanted behaviour.
This patch takes the settings from the workaround.org project, applies
them to submission and submissions, which fixes the current issue.

However I still don't fully understand why.

References:
https://workaround.org/ispmail/bullseye/relay-outoing-email-through-postfix/