Mail Server Software

MTAs are the programs which transport mail from one machine to the other. The traditional MTA is Sendmail, however there are several other choices.

As well as SMTP servers there is a POP server (qpopper) and an IMAP server (Courier-IMAP).


Introduction to Exim

The Exim package contains a Mail Transport Agent written by the University of Cambridge, released under the GNU Public License.

Package Information

Additional Downloads

  • Additional formats of the documentation (text-based docs are shipped with the sources) can be downloaded by following the links shown at

Exim Dependencies


Berkeley DB-4.4.20 (built in LFS) or GDBM-1.8.3 or TDB


X Window System, OpenLDAP-2.3.27, OpenSSL-0.9.8d or GnuTLS, Cyrus SASL-2.1.21, MySQL-5.0.21, PostgreSQL-8.1.3, TCP Wrapper-7.6, and Linux-PAM-

User Notes:

Installation of Exim

Before building Exim, as the root user you should create the group and user exim which will run the exim daemon:

groupadd -g 31 exim &&
useradd -d /dev/null -c "Exim Daemon" -g exim -s /bin/false -u 31 exim

Install Exim with the following commands:

sed -e 's,^BIN_DIR.*$,BIN_DIRECTORY=/usr/sbin,' \
    -e 's,^CONF.*$,CONFIGURE_FILE=/etc/exim.conf,' \
    -e 's,^EXIM_USER.*$,EXIM_USER=exim,' \
    -e 's,^EXIM_MONITOR,#EXIM_MONITOR,' src/EDITME > Local/Makefile &&

This package does not come with a test suite.

Now, as the root user:

make install &&
install -v -m644 doc/exim.8 /usr/share/man/man8 &&
install -v -d -m755 /usr/share/doc/exim-4.61 &&
install -v -m644 doc/* /usr/share/doc/exim-4.61 &&
ln -sv exim /usr/sbin/sendmail

Command Explanations

sed -e ... > Local/Makefile: Most of Exim's configuration options are compiled in using the directives in Local/Makefile which is created from the src/EDITME file. This command specifies the minimum set of options. Descriptions for the options are listed below.

BIN_DIRECTORY=/usr/sbin: This installs all of Exim's binaries and scripts in /usr/sbin.

CONFIGURE_FILE=/etc/exim.conf: This installs Exim's main configuration file in /etc.

EXIM_USER=exim: This tells Exim that after the daemon no longer needs root privileges, the process hands off the daemon to the exim user.

#EXIM_MONITOR: This defers building the Exim monitor program, as it requires X Window System support, by commenting out the EXIM_MONITOR line in the Makefile. If you wish to build the monitor program, omit this sed command and issue the following command before building the package (modify Local/eximon.conf, if necessary): cp exim_monitor/EDITME Local/eximon.conf.

ln -sv exim /usr/sbin/sendmail: Creates a link to sendmail for applications which need it. Exim will accept most Sendmail command-line options.

Adding Additional Functionality

To utilize some or all of the dependency packages, you'll need to modify Local/Makefile to include the appropriate directives and parameters to link additional libraries before you build Exim. Local/Makefile is heavily commented with instructions on how to do this. Listed below is additional information to help you link these dependency packages.

To use a backend database other than Berkeley DB, see the instructions at

For SSL functionality, see the instructions at and

For tcpwrappers functionality, see the instructions at

For information about adding authentication mechanisms to the build, see chapters 33-37 of

For information about linking Linux-PAM, see the instructions in section 7 of

For information about linking database engine libraries used for Exim name lookups, see the instructions at

If you wish to add Readline support to Exim when invoked in “test expansion” (-be) mode, see the information in the -be section of

You may wish to modify the default configuration and send log files to syslog instead of the default /var/spool/exim/log directory. See the information at

Configuring Exim

Config Files

/etc/exim.conf and /etc/aliases

Configuration Information

A default (nothing but comments) /etc/aliases file is installed during the package installation if this file did not exist on your system. Create the necessary aliases and start the Exim daemon using the following commands:

cat >> /etc/aliases << "EOF"
postmaster: root
exim -v -bi &&
/usr/sbin/exim -bd -q15m


To protect an existing /etc/aliases file, the command above appends these aliases to it. This file should be checked and duplicate aliases removed, if present.

The /usr/sbin/exim -bd -q15m command starts the Exim daemon with a 15 minute interval in processing the mail queue. Adjust this parameter to suit your desires.

Boot Script

To automate the running of exim at startup, install the /etc/rc.d/init.d/exim init script included in the blfs-bootscripts-20060910 package.

make install-exim

The bootscript also starts the Exim daemon and dispatches a queue runner process every 15 minutes. Modify the -q<time interval> parameter in /etc/rc.d/init.d/exim, if necessary for your installation.


Installed Programs: exicyclog, exigrep, exim, exim-4.43-2, exim_checkaccess, exim_dbmbuild, exim_dumpdb, exim_fixdb, exim_lock, exim_tidydb, eximstats, exinext, exipick, exiqgrep, exiqsumm, exiwhat, and optionally, eximon, and eximon.bin
Installed Libraries: None
Installed Directories: /usr/share/doc/exim-4.61 and /var/spool/exim

Short Descriptions


cycles Exim log files.


searches Exim log files.


is a symlink to the exim-4.43-2 MTA daemon.


is the Exim mail transport agent daemon.


states whether a given recipient address from a given host is acceptable or not.


creates and rebuilds Exim databases.


writes the contents of Exim databases to the standard output.


modifies data in Exim databases.


locks a mailbox file.


removes old records from Exim databases.


generates mail statistics from Exim log files.


queries remote host retry times.


selects messages based on various criteria.


is a utility for selective queue listing.


produces a summary of the messages in the mail queue.


queries running Exim processes.


is a start-up shell script for eximon.bin used to set the required environment variables before running the program.


is a monitor program which displays current information in an X window, and also contains a menu interface to Exim's command line administration options.

Last updated on 2007-01-15 18:08:14 -0600