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Likely fix

Fix: Outlook.com not sending in browser

Outlook.com can fail to send because of browser issues, attachments, account limits, storage problems, extensions, or a temporary Microsoft service problem.

Quick answer

Try a simple no-attachment email, use a private window or another browser, remove large attachments, and check whether your mailbox storage is full.

Important warning

If Microsoft temporarily restricts the account for unusual sending activity, you may need to verify the account before sending again.

Try this

  1. 1 Check that your internet connection works.
  2. 2 Try sending a simple email with no attachment.
  3. 3 Remove large attachments.
  4. 4 Refresh Outlook.com.
  5. 5 Try a private or incognito window.
  6. 6 Disable browser extensions temporarily.
  7. 7 Try another browser.
  8. 8 Check mailbox or OneDrive storage if attachments are involved.

Common causes

Large attachment.

Browser extension conflict.

Browser cache problem.

Mailbox storage issue.

Account sending limit or restriction.

Temporary Outlook.com service issue.

What to check next

  • Check whether a no-attachment email sends.
  • Check Outlook.com in another browser.
  • Check whether your mailbox is full.
  • Check whether the account asks for verification.
  • Check whether Outlook works on another device.

FAQ

Why is Outlook.com not sending emails?

The cause may be a large attachment, browser issue, full storage, account restriction, or temporary Outlook service problem.

Can Outlook.com block sending?

Yes. Accounts can be temporarily restricted if unusual sending activity is detected.

Should I try another browser?

Yes. Another browser or private window helps test whether extensions or cached data are causing the problem.

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Fix: Email won’t send with attachment

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Fix: Gmail app not sending

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