Inspect the stuck message
- Open Outbox and look for a very large attachment or malformed recipient address.
- Move the message to Drafts, reduce the attachment, and try again.
- Do not keep pressing Send because duplicate copies may leave later.
Check connection and account status
- Turn off Work Offline on the Send/Receive tab.
- Respond to password or account warnings shown in Outlook.
- Send a small test from the provider webmail to confirm the mailbox itself works.
Repair the application side
- Restart Outlook and the computer after updates.
- Check that the account has storage available and is not blocked by an administrator.
- Repair or recreate the profile only after mail is confirmed safely stored on the server.
Stop guessing when the problem keeps coming back
Get help if several users cannot send, Outlook repeatedly asks for a password, or profile repair may risk local-only folders.