Hi,
I tried to do a migration from Exchange 2007 to Exchange 2013 about 2 months ago. I used this document http://blogs.technet.com/b/meamcs/archive/2013/07/25/part-1-step-by-step-exchange-2007-to-2013-migration.aspx
But I also used this technet one http://technet.microsoft.com/en-us/library/jj898581(v=exchg.150).aspx
However when bringing up the Exchange 2013 mail server there was no mail flow (when using the default receive connectors) after moving all the mail boxes from Exchange 2007 which meant I had to move all the mailboxes back. Infact there was no mail flow within the Exchange 2013 server (I.E. when emailing from user1 to user2 that were both hosted on Exchange 2013 the mail would not send, it would stay in the outbox of user1). When I discovered that there was a mail flow issue I started googling and change a whole bunch of things and now I cannot remember what I changed and what the defaults values are. What is the best way to move forward from here. We are currently still running Exchange off the Exchange 2007 server but I still have all the mailboxes on the 2013 server so I cannot uninstall exchange 2013 to start over.