Stalwart and other similar projects might be decent to use, but they lack one detail which is a deal-breaker for me: maildir format for storage. It’s really easy to move between installations and even between different servers, easy and efficient to back up, doesn’t require any fancy databases or anything to be in order and it just works. Sure, it might need few megabytes more memory and search times might be couple milliseconds longer but it just works. My personal maildir has been around from at least 2008 and it’s moved around between servers multiple times without any hiccups ever.
Stalwart and other similar projects might be decent to use, but they lack one detail which is a deal-breaker for me: maildir format for storage. It’s really easy to move between installations and even between different servers, easy and efficient to back up, doesn’t require any fancy databases or anything to be in order and it just works. Sure, it might need few megabytes more memory and search times might be couple milliseconds longer but it just works. My personal maildir has been around from at least 2008 and it’s moved around between servers multiple times without any hiccups ever.