I've recently set up a Exchange 2013 environment in order to move the users away from Exchange 2007 and moved a pilot group to the 2013 environment and some of the users emails are going missing.
If someone in the 2007 environment emails a user that is now in the 2013 environment we are are getting undeliverable like this:
Ex13.domain.local Remote Server returned '554 5.2.0 STOREDRV.Deliver.Exception:NotSupportedWithServerVersionException; Failed to process message due to a permanent exception with message The mailbox of user 2013user@domain.local[1] that is located on a server that is running version 8 can't be opened on a server that is running version 15. NotSupportedWithServerVersionException: The mailbox of user 2013user@domain.local[2] that is located on a server that is running version 8 can't be opened on a server that is running version 15. [Stage: CreateSession]'
Have found the emails in a queue on the 2007 server with the error message: 451 4.7.0 Temporary server error. Please try again later. PRX4
Doesn't happen for all users and is sporadic, has anyone seen this before?
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