How do I Receive email from domain admin@a.a.net to admin@a.net! i use no-ip dynamic dns
There is no external email server but just my internal!
Are you looking for an answer how to configure this in UCS (basically you have to define all domains and addresses as documented in https://docs.software-univention.de/manual-4.3.html#mail::management::domains ff) or how to set up the external receival?