The Ada Milter API is a binding to Libmilter, the Sendmail mail filtering API. A milter is a daemon that assists a Mail Transfer Agent, such as Sendmail or Postfix, in checking messages and deciding whether to accept, reject or modify them. This binding lets you write milters in Ada.
The current version matches the Libmilter that comes with Sendmail 8.13.8 in terms of features. Features introduced in later Libmilter versions are not yet supported.