Beyond Linux^® From Scratch - Version 8.1

Chapter 21. Mail Server Software

Prev
Dovecot-2.2.32
Next
Postfix-3.2.2
Up
Home

Exim-4.89

Introduction to Exim

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

This package is known to build and work properly using an LFS-8.1 platform.

Package Information

Download (HTTP): http://mirrors-usa.go-parts.com/eximftp/exim/exim4/exim-4.89.tar.xz
Download (FTP): ftp://ftp.exim.org/pub/exim/exim4/exim-4.89.tar.xz
Download MD5 sum: b569ec80c495dffc54545895e680ed61
Download size: 1.6 MB
Estimated disk space required: 14 MB
Estimated build time: 0.2 SBU

Additional Downloads

Additional formats of the documentation (text-based docs are shipped with the sources) can be downloaded by following the links shown at http://exim.org/docs.html.
Recommended patch (prevents triggering CVE-2017-1000369 by using exim commands): http://www.linuxfromscratch.org/patches/blfs/8.1/exim-4.89-avoid_mem_clash-1.patch

Exim Dependencies

Required

Recommended

Optional

Berkeley DB-6.2.32 or TDB (alternatives to GDBM, built in LFS), Cyrus SASL-2.1.26, libidn-1.33, Linux-PAM-1.3.0, MariaDB-10.2.8 or MySQL, OpenLDAP-2.4.45, GnuTLS-3.5.14, PostgreSQL-9.6.4, SQLite-3.20.0, X Window System, Heimdal GSSAPI, and OpenDMARC

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/exim

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:

patch -p1 -i ../exim-4.89-avoid_mem_clash-1.patch &&
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 '/SUPPORT_TLS/s,^#,,'                       \
    -e '/USE_OPENSSL/s,^#,,'                       \
    -e 's,^EXIM_MONITOR,#EXIM_MONITOR,' src/EDITME > Local/Makefile &&
printf "USE_GDBM = yes\nDBMLIB = -lgdbm\n" >> Local/Makefile &&
make

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-4.89    &&
install -v -m644 doc/* /usr/share/doc/exim-4.89 &&
ln -sfv exim /usr/sbin/sendmail                   &&
install -v -d -m750 -o exim -g exim /var/spool/exim

Command Explanations

sed -e ... > Local/Makefile: Most of Exim's configuration options are defined 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.

printf ... > Local/Makefile: Setting those variables allows to use GDBM instead of the default Berkeley DB. Remove this command if you have installed Berkeley DB-6.2.32.

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.

SUPPORT_TLS=yes: This allows to support STARTTLS connexions. If you use this option, you need to select whether OpenSSL or GnuTLS is used (see src/EDITME).

USE_OPENSSL_PC=openssl: This tells the build system to use OpenSSL, and to find the needed libraries with pkg-config.

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

install -v -m750 -o exim -g exim /var/spool/exim: Since /var/spool is owned by root and this version of exim drops root privileges early, to run as user exim, it cannot create the /var/spool/exim directory. As a work around, it is created manually.

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 or add additional functionality.

If you wish to build and install the .info documentation, refer to http://exim.org/exim-html-4.89/doc/html/spec_html/ch04.html#SECTinsinfdoc.

If you wish to build in Exim's interfaces for calling virus and spam scanning software directly from access control lists, uncomment the WITH_CONTENT_SCAN=yes parameter and review the information found at http://exim.org/exim-html-4.89/doc/html/spec_html/ch45.html.

To use a backend database other than Berkeley DB, see the instructions at http://exim.org/exim-html-4.89/doc/html/spec_html/ch04.html#SECTdb.

For SSL functionality, see the instructions at http://exim.org/exim-html-4.89/doc/html/spec_html/ch04.html#SECTinctlsssl and http://exim.org/exim-html-4.89/doc/html/spec_html/ch42.html.

For tcpwrappers functionality, see the instructions at http://exim.org/exim-html-4.89/doc/html/spec_html/ch04.html#SECID27.

For information about adding authentication mechanisms to the build, see chapters 33—41 of http://exim.org/exim-html-4.89/doc/html/spec_html/index.html.

For information about linking Linux-PAM, refer to the instructions http://exim.org/exim-html-4.89/doc/html/spec_html/ch11.html#SECTexpcond.

For information about linking database engine libraries used for Exim name lookups, see the instructions at http://exim.org/exim-html-4.89/doc/html/spec_html/ch09.html.

If you wish to add Readline support to Exim when invoked in “test expansion” (-be) mode, see the information in the -be section of http://exim.org/exim-html-4.89/doc/html/spec_html/ch05.html#id2525974.

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 http://exim.org/exim-html-4.89/doc/html/spec_html/ch52.html.

A wealth of information can be also found at the Exim Wiki.

Configuring Exim

Config Files

/etc/exim.conf and /etc/aliases

Configuration Information

Review the file /etc/exim.conf, and modify any settings to suit your needs. Note that the default configuration assumes that the /var/mail directory is world writable, but has the stiky bit set. If you want to use the default configuration, issue as the root user:

chmod -v a+wt /var/mail

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
MAILER-DAEMON: root
EOF
exim -v -bi &&
/usr/sbin/exim -bd -q15m

[Note]

Note

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 automatically start exim at boot, install the /etc/rc.d/init.d/exim init script included in the blfs-bootscripts-20170731 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.

Contents

Installed Programs: exicyclog, exigrep, exim, exim-4.89-3, exim_checkaccess, exim_dbmbuild, exim_dumpdb, exim_fixdb, exim_lock, exim_tidydb, eximstats, exinext, exipick, exiqgrep, exiqsumm, exiwhat, and optionally, eximon, eximon.bin, and sendmail (symlink)

Installed Libraries: None

Installed Directories: /usr/share/doc/exim-4.89 and /var/spool/exim

Short Descriptions

exicyclog	cycles Exim log files.
exigrep	searches Exim log files.
exim	is a symlink to the exim-4.89-3 MTA daemon.
exim-4.89-3	is the Exim mail transport agent daemon.
exim_checkaccess	states whether a given recipient address from a given host is acceptable or not.
exim_dbmbuild	creates and rebuilds Exim databases.
exim_dumpdb	writes the contents of Exim databases to the standard output.
exim_fixdb	modifies data in Exim databases.
exim_lock	locks a mailbox file.
exim_tidydb	removes old records from Exim databases.
eximstats	generates mail statistics from Exim log files.
exinext	queries remote host retry times.
exipick	selects messages based on various criteria.
exiqgrep	is a utility for selective queue listing.
exiqsumm	produces a summary of the messages in the mail queue.
exiwhat	queries running Exim processes.
eximon	is a start-up shell script for eximon.bin used to set the required environment variables before running the program.
eximon.bin	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 2017-08-26 22:03:17 -0700

Prev
Dovecot-2.2.32
Next
Postfix-3.2.2
Up
Home