- Double-check the email server settings.
- Ensure that the correct protocols are being used. (POP3, IMAP, etc.)
- Check for the correct port numbers.
- Check that the email address and password are correct.
- Verify the security settings in place (SSL, TLS, etc.)
- Make sure the outgoing server settings are configured correctly.
- Clear all DNS caches.
- Restart the email application.
- If necessary, use webmail to test server settings.