Email won't send? Fixing "cannot connect to server"

First, narrow it down

• Try webmail (Gmail.com, Outlook.com, or your host's webmail). If sending works there, your account is fine and the issue is the app or device.
• Try a different network. Some hotel and public Wi-Fi blocks email apps.

Common fixes

1. Re-enter your password. Changed it recently? Every phone, tablet and computer needs the new one.
2. Remove and re-add the account in your phone or in Outlook. It refreshes settings that have gone stale.
3. Check the outgoing server settings (for email at your own domain): the SMTP server, port 465 (SSL) or 587 (STARTTLS), and "My outgoing server requires authentication" turned on with the same username and password as incoming.
4. Check your Outbox for a stuck message with a huge attachment. Delete it and send a share link instead.

Write down the error

Note the exact message, like 0x800CCC0E, "authentication failed" or "relay denied". It tells a tech exactly where to look.