The architecture of both qmail and djbdns are excellent. However, the lack of a clear maintenance team means that they fracture whenever a new must-have feature

The architecture of both qmail and djbdns are excellent. However, the lack of a clear maintenance team means that they fracture whenever a new must-have feature comes along. If you need dynamic DNS support, djbdns needs something else to handle it. If you need TLS for your mailserver, qmail needs something to handle it. Greylisting? Something else. If qmail and djbdns had communities the same size as Postfix and Knot, they would be excellent general-purpose choices.