Sending, receiving, and organizing email in Outlook on the web for business
Open Outlook on the web and go to Settings → Account → Storage, then permanently remove enough mail to bring the mailbox below its quota.^1^
Free mailbox space
- Select Settings (gear icon) → Account → Storage.
- Review the folder-size breakdown and clean the largest folders first.
- To find large messages, return to the message list and select Filter → Sort by → Size. Select it again if the smallest messages appear first.
- For messages with attachments you need:
- Select Save to OneDrive beneath the attachment.
- After confirming the file was saved, delete the original message.
- Empty Deleted Items. Ordinary deletion only moves messages there, and that folder continues to count against your storage quota.
- To bypass Deleted Items, select unwanted messages and press Shift+Delete. This permanently deletes them, so verify the selection first.^1^
- Check Settings → Account → Storage again, then send yourself a new test message.
You can also select a repetitive message in the Inbox and use Sweep to remove older or unwanted messages from that sender. Empty Deleted Items afterward, because Sweep alone does not reclaim the storage.^1^
If there still is not enough space
For a work or school mailbox, ask your Microsoft 365 administrator to:
- Enable or provision an archive mailbox so older messages can be moved out of the primary mailbox.
- Review your mailbox quota and license, and provision more space if the subscription permits it.^1^
If Storage shows available capacity but the full-mailbox warning remains, report that discrepancy to the administrator rather than deleting more mail; hidden recoverable items or organizational retention settings may require administrator investigation.
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