exim4-doc-html 4.86-1 (i386 binary) in ubuntu xenial

 Contains specification and filtering documentation in HTML format.
 .
 The Debian exim4 packages have their own web page,
 http://pkg-exim4.alioth.debian.org/. There is also a FAQ list. Local
 information about the way the Debian packages can be configured is
 can be found in /usr/share/doc/exim4-base/README.Debian.gz. This file
 has also information about the way the Debian binary packages are
 built. 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
 .
 exim is a drop-in replacement for sendmail/mailq/rsmtp.