A question that comes up often goes something like this:
"I cannot delete messages in my email inbox. Outlook says "The messaging interface has returned an unknown error when I try. My mail works fine, but I just cannot delete anything. Does someone know a solution?"
There are two things that can cause problems deleting items, the most common is having too many items in the deleted folder. Depending on your version of Outlook, any folder can hold approximately 16,000; 65,000, or unlimited items. When the deleted folder hits its limit, you need to empty it.
The other cause is from an antivirus scanner on the Exchange server and obviously only affect Exchange server accounts.
In either case, the only way to delete items without addressing the cause, is to hold the shift key when you delete to bypass the Deleted items folder.
Published May 4, 2004. Last updated on May 13, 2013.