I thought about how I would fix that retaining the catch-all feature they have.
You can get mail from all non assigned names on your domain on the catch-all assigned account, if you enable that. You should also expect to be able to write from any of those non assigned names with this account.
If your account is the only one connected to that domain, everything is ok.
But if you let's say have 100 users-accounts on this domain, you could build a blacklist for the names that are assigned to other accounts (which would be cached, therefore could have delay), accept that the admin can impersonate all their users or lookup every assigned domain on each send. Am I missing something obvious?
