When reviewing the MAgE.log file for a mailbox that is not synchronizing. The following error is displayed in the log:
Error System.ArgumentOutOfRangeException: index is out of range
This happens when the mailbox was previously part of a legacy agent collection going to Exchange 2010 and then is moved into a collection using the MAgE. The legacy agents use different matching attributes within the SQL Database than the MAgE. For this reason you cannot move the mailbox between the 2 collection types.
RESOLUTION 1
Leave the mailbox in the current mailbox sync collection and move the mailbox after it has been synchronized and switched.
Then move the mailbox to the Exchange 2013 servers after the migration has completed.
RESOLUTION 2
Delete the target mailbox.
Recreate the mailbox using the DSA and put the mailbox into a MAgE collection.
