I set up a new server last week for 3 domains I own, and it was working flawlessly until today.
Now incoming email just disappears as if it never existed, and outgoing email gives this message:
An error occurred during sending the message. (553 5.7.1 : Sender address rejected: not owned by user" no matter what address I’m trying to send from (even my admin account).
Luckily I hadn’t put this server into production yet.
Any ideas what would be causing this?