Sendmail -- Which version

Desite the fact that V8.13 has not been released yet, you still have a choice. Because V8.13.PreAlpha has been running in production on several machines without problems, you will probably be safe to use it yourself. As far as milter support goes, these are a few of the new advantages of V8.13: If you are interested in using V8.13 with this milter, you may download it from sendmail.org.

If you are worried about running an alpha version of sendmail, you may run V8.12 sendmail with this milter. You won't be able to dedicate a milter to a single inbound connection handler, and you won't have access to bad recipients, and you will get warnings when compiling, but otherwise it will run just fine. V8.12 is also available from sendmail.org.