Check that your ISP allows you to run an email server on your network before going any further.
safe setup can be complicated.
Absolutely agree - the biggest no-no is leaving an open relay. You should also be looking at using encryption (TLS 1.2), some form of authentication (SPF, DKIM or possibly DMARC if possible).
I've used HMail as a free email server that runs on both server and desktop OS - Windows 10 is supported. It's likely that a small scale email server for home use will not outgrow the embedded MS SQL DB, so unlikely to need a fully-fledged DB.
SD