Update Rollup 13 for Exchange 2007 Service Pack 3 is now available for direct download.
This Rollup Update fixes the following compatibility issue with Exchange 2013:
- KB2926397 An Edge Subscription file from an Exchange 2013 Edge Transport server is rejected by an Exchange 2007 Hub Transport server
View: Description of Update Rollup 13 for Exchange Server 2007 Service Pack 3
Download: Update Rollup 13 for Exchange Server 2007 Service Pack 3 (KB2917522)