A customer of mine ran into a problem while migrating from Exchange 2007 to 2010. They didn’t receive any internal email. Here are the properties of the default receive connector :
That’s the problem. Make sure you enable Transport Layer Security (TLS) and Exchange server authentication.
When you enable Exchange Server authentication you have to make sure that your FQDN matches your server FQDN (mailserver.corp.local or something like that)
Now you should be able to receive mail. Make sure you edit al your receive connectors (when multiple exchange servers are present in your Exchange organisation)