I thought I was at the point of migrating our mailboxes from 2007 to 2013. I had created a new test mailbox on the 2013 server and changed all the DNS and virtual directories for the legacy on the 2007 server and was able to successfully send mail to the test mailbox out and in both internally and externally. Then I migrated my first mailbox from 2007 to 2013 and things went south.
I CAN NOT:
Send e-mail from a mailbox on the 2007 server to the migrated mailbox on the 2013 server.
Send e-mail from migrated mailbox to external e-mail address.
I CAN:
Send e-mail from the migrated mailbox to a 2007 mailbox and the test mailbox on the 2013 server.
Send e-mail from the internet to the migrated mailbox and the 2013 test mailbox.
I unfortunately am running Exchange 2013 with CU6 (I am already aware of the activesync issue and delegation crash issue but saw the info too late).
Suggestions please!!