While accessing a mailbox via Outlook Web Access – its ends up with this below error
(A problem occurred while you were trying to use your mailbox)
Steps to resolve –
Verify its one mailbox or many mailboxes are having this issue
If its one mailbox try moving the mailbox to a different database and check if that resolves.
Verify mailbox is accessible via Outlook .
In my case . I was having Event generated for the particular user
Log Name: Application
Date: 4/19/2014 11:22:30 AM
Event ID: 9646
Task Category: General
Mapi session "b3cb9ed0-e667-4568-997e-b5e518f6bb70: /o=CareExchange/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=Sathesh. | CareExchange70c" exceeded the maximum of 16 objects of type "session".
- On the server that is running the Exchange Server 2010 Mailbox role, click Start, click Run, type regedit, and then click OK.
- Locate and then click the following key in the registry:
- On the Edit menu, point to New, and then click DWORD Value.
- Type Maximum Allowed Service Sessions Per User, and then press ENTER.
- On the Edit menu, click Modify.
- Type the decimal value that specifies the number of sessions to 28 (Max is 32), and then click OK.
- Exit Registry Editor.
Make sure you don’t put it to max . if there are many users . it can make the server to be unstable as all the users will be able to make 28 non-mapi sessions to the server .
Non Mapi sessions are IMAP, POP, Outlook Web Access, Microsoft Exchange ActiveSync (EAS), or Exchange Web Services (EWS).
Now mailbox is accessible .
(you can try doing a IISreset if its still inaccessible)
Reference KB –