Authentication Milter

Overview

Our MX servers run a mail filter (milter) on incoming email that runs the alphabet soup of checks - DKIM, SPF, DMARC, etc.

For some checks (SPF, DKIM) it’s responsible for adding headers indicating whether the message passed those checks. For others (e.g. DMARC) it is responsible for rejecting the message if it fails to pass.

We originally used the debian packaged opendmarc and opendkim, but the upstream packages are not well maintained and we noticed some incoming email messages caused opendmarc to crash, so we have switched to authentication_milter.

Unfortunately, it is not in debian and installing it is a bit painful.

Creating missing Debian perl modules

The recommended way of installing the package is via cpan (e.g. cpanm Mail::Milter::Authentication).

But, first we install as many dependencies as we can via debian (and also libssl-dev which is required to build the openssl packages.

The (some? not sure if this is all) perl modules not packaged in debian (or with versions that are too old) are:

  • Lock::File
  • HTTP::Tiny::Paranoid
  • Alien::Build
  • Alien::Build::Plugin::Download::Gitlab
  • Mozilla::CA
  • Alien::Libxml2
  • Mock::Config
  • Mail::BIMI
  • Mail::DataFeed::Abusix
  • Mail::Milter::Authentication