This seemed to already be technically supported but the validation is now stricter and the admin is more helpful:
* Postfix seems to allow @domain.tld as an alias destination address but only if it is the only destination address (see the virtual man page).
* Allow @domain.tld if it is the whole destination address string.
* Otherwise, do not allow email addresses without local parts in the destination.
* In the admin, add a third tab for making it clear how to add a domain alias.
closes#265
For now use the command-line tools/mail.py if you need it.
see #200
Revert "Changed incomming-email-input to type text"
This reverts commit 9631fab7b2.
