We have recently migrated from Exchange 2007 to Exchange 2013. At this point both servers are up and running with just a couple of mailboxes on the 2007 server. Role are listed below.
• 2007 Server – Mailbox, Client Access, Hub Transport
• 2013 Server – Mailbox, Client Access
Internally, we have an IIS server on the domain that support an intranet site. This site can send e-mail both internally and externally. After the migration external mail now generates this error: Mailbox unavailable. The server response was: 5.7.1 Unable to relay
I have set up a receive connector following the documentation online, but I just can’t get external mail from this IIS server working. Is there anything else I might need to do? This worked just fine before the migration with the same receive connector rules.