Outlook: Deleted Items Reappear

In Outlook, using a mailbox hosted in Office 365 (Exchange Online) or in on-premises Exchange, deleted items may reappear, or appear inconsistently:

1. Items that were deleted via Outlook do not appear in the local mailbox cache, but appear online;

2. Items deleted in cached mode appear when using Outlook in non-cached mode;

3. Items are visible using Outlook Web Access or IMAP; or

4. Items reappear after Outlook has a chance to resync the mailbox. A deleted folder called, say, Sales Reports may reappear as Sales Reports (1).

This may occur if a large number of deletions have been performed, and the dumpster is full, or large.

When an item is deleted permanently, either by using Shift-Del or removing an item from the Deleted Items folder, the item goes into the “dumpster”, which is a hidden repository of recently-deleted items, and can be retrieved using the Recover Deleted Items function. Items in the dumpster are eventually purged (default is 30 days), and do not contribute to the mailbox quota. However the dumpster has its own storage limitation, which can vary. If the dumpster is full or has a lot of items, any further deletions fail and the item will reappear.

One remedy is to wait 30 days to let items disappear from the dumpster, or purge the items manually via Recover Deleted Items; this can take some time, so may be best left running overnight.

See also Outlook — Description of Deletion Methods.