Synology NAS Mail Server Setup

I have a Synology NAS and want to run my own mail service on it using the Synology Mail Server Classic package. The NAS sits behind a static public IP, I own the domain, and I can edit all DNS records through cPanel at my ISP. I have watched a few tutorials but need real-time guidance—every step will happen on my laptop through a remote session and I will keep all credentials local, so you’ll be directing me rather than logging in yourself.

Scope of help I need
• Configuring DNS settings (A, MX, SPF, DKIM, DMARC, PTR)
• Installing and configuring the Synology Mail Server Classic software and any required companion packages (Postfix/Dovecot components inside DSM)
• Setting up security and encryption, including SSL/TLS certificates and SMTP authentication
• Testing end-to-end delivery, spam score, and client connections (IMAP/SMTP)

I’d also like you to double-check everything, including creating at least one mailbox with me to be sure the workflow is clear.

Deliverable
A fully functioning, secure mail server that passes external tests and delivers/receives mail reliably, with written notes of any settings we change so I can maintain it later.

If you have walked someone through this exact process before and can stay on a call or chat until the tests are green, let’s get started.