We are currently in co-existence between Exchange Server 2007 RU13 and Exchange Server 2013 CU5
A few hundred users have migrated ok so far but for some a few days/weeks later some old meeting requests are resent
eg a meeting from 10-Jun-2013 was resent on 11-Nov-2014 from someones calendar
The only recent change made (post the mailbox being migrated) was a 7 year retention policy being applied to their mailbox
However, this should have no effect as the appointments are well within that period
could this be related? has anyone seen this before? there is no information in the eventlogs
thanks
shapi