Which Sendmail versions to use for Milter, OS considerations ?

Between the sendmail 8.11.x and 8.12 series, Milter has been vastly fixed and improved
  • avoid 8.11.x and early 8.12 versions
  • the latest version is always the better choice (bug-fixes, more antispan/LDAP support and Milter improvements)
Check these links for reasons for using the latest sendmail version :
Getting the latest Sendmail running is easy on some Operating Systems (FreeBSD,some Linux distributions such as PLD, Debian keep their packages up to date). If you can't find some package for the latest sendmail version for your operating system, ask your Unix/Linux vendor so they release new packages. Of course You can also compile sendmail by hand (so it includes only the features you want).
Just make sure your site.config.m4 contains :
APPENDDEF(`conf_libmilter_ENVDEF', `-DMILTER')
APPENDDEF(`conf_sendmail_ENVDEF', `-DMILTER')

It is not recommended to run Milter filters as root. As written in libmilter/README (one of Milter's must read documents along with the libmilter/docs HTML pages), libmilter does not require this to communicate with sendmail. It is therefore wise to put :
in your site.config.m4
To make sure your sendmail binary is compiled with Milter support just run :
  • sendmail -d0.13 -bv root | grep MILTER (works for sendmail 8.10.x, 8.11.x,8.12.x).
  • or sendmail -d0.1 -bv root | grep MILTER (works for sendmail 8.12.x)