Your mailbox is full

What to do when Outlook says you are out of space.

Updated September 21, 2026

A full mailbox stops new messages from arriving. Tell us if you see this message. There are safe ways to free space, and something unusual may be filling it.

Free some space yourself

  • Empty the Deleted Items and Junk Email folders.
  • Search for hasattachments:yes, sort the results by size, and delete old messages with big files.
  • Save important attachments in OneDrive first, then delete the email.
  • Do not delete anything you may need for records or legal reasons. Ask your manager or us first.