Outlook calendar events disappear after some months

issue:  Customer complained that Outlook calendar events disappear after some months

 

2 key things to check as you troubleshoot this:

 

a. autoarchive setting

b. mobile device synchronization

 

Note: Outlook does not delete things from the calendar automatically unless you have configured it to do so. 

 

Resolution:

 

verify autoarchive setting by Right-clicking the Calendar folder , choose Properties.  Select the AutoArchive tab and look to see if autoarchiving is enabled.  If so, disable it.

If AutoArchive is not the issue, confirm is customer synchs with a hand-held device?  That can be a contributing factor.
Mobile devices usually delete the events while the synchronization software ensures event is deleted in Outlook.