/
Outlook - Mailbox Is Full

Outlook - Mailbox Is Full

Problem

Users may receive a Mailbox is full warning even after deleting email. This can happen because deleted items still consume space until they are permanently removed, and in some cases deleted items are retained in a hidden Recoverable Items area due to retention/compliance settings.

Solution

  1. Use Outlook on the web to confirm actual mailbox storage capacity.

    1. Go to outlook.office.com

    2. Click on the gear icon on the top right

    3. In the Settings menu, click on Account > Storage.

      image-20260309-205245.png

    4. View what is using up your storage.

  2. Delete unnecessary messages from high-usage folders (Inbox, Sent Items, large subfolders).

  3. Permanently remove deleted mail:

    1. Empty the Deleted Items folder.

    2. Empty the Junk Email folder.

  4. If the mailbox is still near/full, check the Recoverable Items area:

    1. In Deleted Items, use Recover items deleted from this folder and remove/purge items as needed.

      image-20260309-205413-20260309-215358.png

  5. Reduce large content:

    1. Find messages with large attachments and save needed files outside email (such as OneDrive or SharePoint), then delete the messages (and re-empty Deleted Items/Junk).

  6. If Online Archive is enabled for you by IT, move older messages to the Online Archive mailbox.

  7. Allow time for mailbox quota/storage to update and re-check after synchronization (may take some time in some cases). If the warning persists, contact IT.