@delta Fastest and simplest option would be Stalwart which gives you everything in a single binary. It's all written in Rust. Backend can be as simple as Sqlite or RocksDB
The speed and simplicity of this stack (vs the overwhelming complexity of configuration for Postfix/Exim/Sendmail and Dovecot/Cyrus) is incredibly alluring
Stalwart will do everything for you except your DNS configuration. Yes, it even handles your TLS certs.