exim4-daemon-light 4.88-5ubuntu1 (amd64 binary) in ubuntu zesty

 Exim (v4) is a mail transport agent. This package contains the exim4
 daemon with only basic features enabled. It works well with the
 standard setups that are provided by Debian and includes support for
 TLS encryption and the dlopen patch to allow dynamic loading of a
 local_scan function.
 .
 The Debian exim4 packages have their own web page,
 http://wiki.debian.org/PkgExim4. There is also a Debian-specific
 FAQ list. Information about the way the Debian packages are
 configured can be found in
 /usr/share/doc/exim4-base/README.Debian.gz, which additionally contains
 information about the way the Debian binary packages are built. The
 very extensive upstream documentation is shipped in
 /usr/share/doc/exim4-base/spec.txt.gz. To repeat the debconf-driven
 configuration process in a standard setup, invoke dpkg-reconfigure
 exim4-config. There is a Debian-centered mailing list,
 pkg-exim4-users@lists.alioth.debian.org. Please ask Debian-specific
 questions there, and only write to the upstream exim-users mailing
 list if you are sure that your question is not Debian-specific. You
 can find the subscription web page on
 http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users