[MM3-users] Where does sender postorius@ come from?

I just realized, that mails for registering an account and/or resetting ones password are obviously sent from postorius@SERVE_FROM_DOMAIN. Why are they not sent from MAILMAN_ADMIN_EMAIL?

The problem is:

• an account is trying to register with a mailaddress from a HostEurope-server
• HostEurope-Servers are doing Sender-Callouts (bad practise :-D) to verify that a mailaccount exists
• mail is then bouncing, b/c those are not answered (shoud I?): status=bounced (host [80.237.138.5] said: 550-Sender verification is required but failed.
• bounce then can't be processed, since mailaccount does not exist :-D status=bounced (mail for SERVE_FROM_DOMAIN loops back to myself)

Am I missing something are shouldn't it be better to send those mails from MAILMAN_ADMIN_EMAIL? (I don't want to mess with these sender callouts or change anything, HostEurope has been a little bit of a pain in the ... with mailinglists and not much help at all).

Thanks in advance, Jens.