Reconfigure Mail Service on Server Linux

I'm seeking an experienced professional to completely reconfigure my mail service on my server due to ongoing authentication issues. Although the system functions in principle, setting up accounts via Outlook has been problematic, while Thunderbird works but with frequent authentication issues.

Key Requirements:
- Reconfigure mail service to operate exclusively through server.domain.de.
- Remove the mail.domain.de subdomain entirely.
- Ensure Mailcow is accessible via server.domain.de with reliable email access.
- Implement SSL encryption for the entire setup.
- Ensure seamless support for Outlook email client.
- Use OAuth as the preferred authentication method.

Ideal Skills and Experience:
- Expertise in server management and mail service configuration.
- Experience with CyberPanel and Cloudflare integration.
- Proficiency in setting up and troubleshooting mail servers, especially with Outlook.
- Strong knowledge of SSL encryption and OAuth authentication.

I am looking forward to resolving these issues and achieving a stable and secure mail service setup.