server admin

hello,

I have mac os sierra on my late 2009 iMac. I would like to use something like server admin to configure a mail server for my custom domain on my iMac without buying any sw. Can someone point me to any Kb which tells me step by step on how to do so? This is going to be a 1 domain/1 user mail server without remote access.. I would also be interested in protecting it from spams and various other attacks with minimal hw/sw at my end.

thanks

-kamal

System Version: macOS 1

Kernel Version: Darwin 16.7.0

Boot Volume: Macintosh HD

Boot Mode: Normal