Email Stalwart: Personal Email Server Stalwart made one of the hardest systems to manage, the easiest thing I've done in a while. Bonus is automatically encrypting all incoming email at rest using OpenPGP key or S/MIME certificate.
Email S/MIME Certificate Being able to encrypt your emails and sign them so others know you personally sent them, is worth the struggle.
Security Sender Authentication Sender Authentication is a standard that uses DNS to publicly verify your email messages.