Till Exchange 2010 Sp2 Ru3 – MRM never gets applied on Calendar and Tasks
But in the release of Exchange 2010 Rollup 4
This has been included.
Present – Exchange 2010 Sp2 Ru4 or above
what you should know is
Retention policies do work for the Calendar and Tasks folders in an Exchange Server 2010 SP2 Ru4 or above environment
So if you have a policy which is applied for all Folders in the mailbox in the past – Once you upgrade to Exchange 2010 Sp2 ru4 or above
Retention Policy will apply on “Calendar and Tasks” where the old items are going to expire and retention action will take place as per the policy
So all of a sudden your old calendars and tasks got disappeared or got deleted . This will be the most possible reason.
you can find the items as per the retention action has been taken place.
If you feel “Calendar and Tasks” should not get deleted , If you feel this will not suit your environment.
Before applying the Exchange 2010 sp2 Rollup 4 or upgrading above Exchange 2010 Sp2 Rollup 4
There is a registry tweak available to disable them from the server end. Where this design change won’t get effect in your environment.
Open Regedit on you all your mailbox servers
Start- Run – Regedit
Browse to the below location
Create a New “DWORD (32-bit) Value”
Enter the Value – ELCAssistantCalendarTaskRetentionEnabled
To disable this Design Change – (MRM won’t apply on Calendar and Tasks)
Type Decimal Value – 0
Later, To enable this Design Change – (MRM will apply on Calendar and Tasks)
Type Decimal Value – 1
Hope this article will clear some confusions !!