Fix for "The message store has reached its maximum size" message in Outlook

Fix for "The message store has reached its maximum size" in Outlook

Got this for one user and all mailbox size was within limits and quotas. Issues was a bad .OST file.

It was a corrupt .OST file. Close outlook, rename the .OST file in C:\Documents and Settings\username\Local Settings\Application Data\Microsoft\outlook and then re-open outlook. It will re-create the OST file for them.