notqmail is the collaborative Open Source successor to qmail and netqmail. It begins with stable, compatible, small releases to which existing qmail users can safely update, and aims to become a more extensible, more easily packaged, and more modern Mail Transport Agent suitable for most needs.
qmail's design principles haven't always prevented bugs or holes, nor have they always made adding new functionality easy. But pretty often we get both. And that's why we continue to invest in this codebase.