Is there a limit on the amount of time that MS Outlook Calendar retains past dates and appointment data? I work with users whose past data disappears after about one month. For example, after August passes, Calendar will retain its date and appointment data for August for about 30 days but then it disappears. I can find no setting in Outlook that affects the amount of time that the Calendar retains data. Is this an Exchange setting? I administer an Exchange server for 40 users. Help on this would be appreciated. Thank you.

From another forum:

With Exchange there are 3 possible causes:
1. Mailbox manager is set to clear out old appointments - this is applied by
policy and can affect all mailboxes or those within a group.
2. Users set up Autoarchive - this is set per user.
3. Syncing with a deceive such as a blackberry or similar mobile device. The
default for blackberry is 60 days, not sure for the other device types.