How do I troubleshoot an issue with outgoing emails getting stuck in the queue?

1. Check the queue on your mail server
2. Check the mail routing setting and DNS
3. Check the recipient email for any rejected email
4. Check your email server authentication
5. Check your email server settings
6. Check your spam filter rules
7. Analyze email rejection reports
8. Update firewall rules and verify SMTP port settings
9. Analyze the log files
10. Check the authentication methods