So i have to use a shared domain during migration from Zimbra
to O365.
MX points to Zimbra
, but is also configured to enable outgoin emails from O365 to the world in the same domain. I've configured a connector on O365 to the zimbra (it works), and created contacts for not-yet-migrated users.
The plan is, that during migration, the incoming mail comes to zimbra and is redirected to O365 to onmicrosoft domain, for migrated users.
When i send email from O365 to anywhere (except my domain) it works correctly. When I send to anyone within company, that is still on zimbra, I get either of the errors:
550 5.7.1 ... Relaying denied
553 5.7.1 : Sender address rejected: not logged in
Zimbra
clearly blocks my user, as it already exists within its server, but I don't know, where to start to unlock it? I've done similar things with other services before, but most didn't care about that.