How to Setup an Email Firewall

From ReduxWiki

This will explain setting up Exim, MailScanner, SpamAssassin, ClamAV, and other SpamAssassin Modules in order to filter out both spam and Viruses before they reach your server.

We will use /usr/src for downloading and installing all tarballs, so first:

cd /usr/src

[edit] Download the exim source tarball

wget ftp://ftp.fsckit.net/pub/exim/exim4/exim-4.32.tar.gz

[edit] unpack Exim using tar

tar -zxvf exim-4.32.tar.gz

[edit] Move into the Exim directory

cd exim-4.32

Now we need to create a Local/Makefile file to build Exim, use your favorite editor and create the file /usr/src/exim-4.32/Local/Makefile in it, copy and paste this:

BIN_DIRECTORY=/usr/exim/bin
CONFIGURE_FILE=/usr/exim/configure
EXIM_USER=exim
LOOKUP_DBM=yes
LOOKUP_LSEARCH=yes
ROUTER_ACCEPT=yes
ROUTER_DNSLOOKUP=yes
ROUTER_IPLITERAL=yes
ROUTER_MANUALROUTE=yes
ROUTER_QUERYPROGRAM=yes
ROUTER_REDIRECT=yes
SPOOL_DIRECTORY=/var/spool/exim
SPOOL_MODE=0640
TRANSPORT_APPENDFILE=yes
TRANSPORT_AUTOREPLY=yes
TRANSPORT_PIPE=yes
TRANSPORT_SMTP=yes