There are several interesting external resources that could be useful.
Some of the documentation here is valid for openQmail in general or most cases, some of it is may be useful to find a partial solution.
The djb way
- a quite good documentation along djb's way and software
- mostly outdated, some tips are may be still useful
- some related articles and tutorials         Important!
The community provides good stuff too.
There are some “big” patches and sites with multiple patches. The “big” patches are not used by openQmail, but some ideas are “stolen”.
Other forks of (net)qmail
The forks with active maintenance have dependencies which are not acceptable by openQmail's philosophy.
, an active maintained fork by Manvendra Bhangui
, active maintained by Erwin Hofmann, a bit to academic and over-featured, away from practice
- the smtpplugins patch (qmail-spp) was derivative from here, otherwise the project seems to be dead