I've posted it here. I've been testing it with 2.1.6-alpha
The README file should describe everything. This is a module providing an
optional utility function intended for (but not limited to) mod_smtpd. The
function allows the user to query DNS based blocklist databases, both DNSBL
and RHSBL style, for arbitrary data. This can be used for all kinds of
filtering and anti-spam use, including score systems such as spamassassin.
In the case of SMTP the query can be the client's IP, client's host name,
and the domain used in the sender's address. I know that Rian is currently
redesigning much of mod_smtpd but for demonstration purposes I have
included code that brings spam blacklisting functionality to mod_smtpd 0.1.
If a blacklisted client connects, they will be denied service. It is more
standard however to have these checks done after RCPT TO, at which time the
envelope domain can also be checked against RHSBL.
It would be great to hear some feedback as I am very new to writing these
modules. I've tried to use the proper apr_ calls whenever available.