[Greylist-users] greylist lib in C?

[Steven Grimm]

Check out Martin Dempsey's implementation for qmail:

http://www.digitaleveryware.com/projects/greylisting/

It's a relatively simple standalone C program (no C++) that is called
by the qmail SMTP server to check the status of a triplet. It uses
MySQL, but you could probably swap that out for a backend of your
choice without tons of effort.

-Steve