mailalias has priority over mailbox if they both exist
If I create a mailbox user@domain.tld and also create an alias for the same address (user@domain.tld -> user2@domain2.tld), only the alias is active, and mail is not deliverd in the mailbox. I think that this behaviour should be made clear to the client if a mailbox or alias is created, while there is already an alias or mailbox for the address. I expected to have the mail as well in the mailbox as on user2@domain2.tld.