I'm running my own public DNS server and now working towards creating my own mail server for the domain.

I have added the mx record into DNS as mx1.example.com. However, mx1 obviously doesn't point to anything yet.

The actual mail server is called mailbox1.example.com. I have an A record for it with a static IP.

So would I just create a CNAME for mx1 to point to mailbox1?