Message Stats is reporting increased volumes of mail flow since beginning of migration to new exchange version.
Co-existing exchange versions 2010 and 2013
During a migration from exchange 2010 to 2013.
Configuration is set to ensure all Email transits the Exchange 2010 infrastructure before going to the mailboxes on Exchange 2013
According to this deployment, Message Stats would count at least two mail flows.
1) Server 2010 to server 2013
2) Server 2013 to server 2013
