one client (it's allways the same client) has often problems with mapi sessions killed by the exchange server. The Application Eventlog on the exchange logs eventid 9646 with source MSExchangeIS:
Die MAPI-Sitzung '/o=xx/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=xxxx' hat die maximal zulässige Anzahl von 250 Objekten vom Typ 'objtMessage' überschritten.
The client has no eventlogs logged about this error.
I looked for installed Outlook Add-Ins and found the default add-ins from microsoft, an adobe pdf add-in (which I deactivated because it's not needed) and an "Octopus" plugin from telekom.
Octopus is a CTI-application that connects to Outlook. My guess is, that Octopus (or its add-in) causes this error because this client has over 1100 contacts.
My question is: how can I find out, which application/add-in causes this problem?
Edit: I already looked at eventid.net but nothing helped.
Edit2: Exchange-Cache-Mode is not used nor are there any shared folders / mailboxes open.
Disable the add-ins one at a time until the errors ceased to be logged.
We found this was the symptom when users were - using Cached Exchange Mode - had it configured to download public folder favourites - had many public folders in their favourites
We found no fix for it, we just had to tell users not to add too many PFs to their favourites or turn off the cached mode
Check out this technet blog post by Jeff Stokes, on troubleshooting the issues.