This page contains pointers to documentation available for the Debian exim4 packages. Debian has "official" exim 4 packages, and exim 4 is Debian's default MTA. The configuration scheme that is used by the Debian exim 4 packages by default is quite different from what you might expect.
/usr/share/doc/exim4-base/README.Debianon your system (in text and/or html form depending on your package version), giving a short introduction to the specialities of the Debian exim 4 packages. This documentation also includes information about how to get rid of the elaborate configuration scheme if you want to configure your exim in a more conservative way.
Please try to determine whether you have an issue with exim itself or with Debian's packaging and do not ask Debian specific questions on exim-users. If in doubt, ask on pkg-exim4-users_. People will point you towards exim-users if you have a problem with the exim 4 upstream.
Note carefully that the package name for the current version is exim4 -- if you install the exim package, you will get Exim version 3. This is required to cleanly support upgrades from older versions of Debian GNU/Linux.
Debian offers two flavours of the exim4 Daemon: exim4-daemon-light is a very basic exim which has the basic features and TLS encryption, while exim4-daemon-heavy has most advanced features like LDAP, MySQL and PostgreSQL, SPA SMTP authentication, an embedded Perl interpreter and exiscan-acl.
The Debian exim4 packages use a debconf-driven configuration scheme which might look strange to the experienced exim user.
The exim wiki, hosted on github. You need a github login to edit. Please add to and improve the content of this wiki