Exim-4.92.1

#### Beyond Linux® From Scratch (systemd Edition) - Version 9.0

### Chapter 21. Mail Server Software

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# Exim-4.92.1

## 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-9.0 platform.

### Package Information

- Download (HTTP): https://ftp.exim.org/pub/exim/exim4/exim-4.92.1.tar.xz

- Download (FTP): ftp://ftp.exim.org/pub/exim/exim4/exim-4.92.1.tar.xz

- Download MD5 sum: c047cb66e60557cec8f2dbc558cb5707

- Download size: 1.7 MB

- Estimated disk space required: 15 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.

### Exim Dependencies

#### Required

libnsl-1.2.0 and PCRE-8.43

#### Optional

TDB (alternative to GDBM, built in LFS), Cyrus SASL-2.1.27, libidn-1.35, Linux-PAM-1.3.1, MariaDB-10.4.7 or MySQL, OpenLDAP-2.4.48, GnuTLS-3.6.9, PostgreSQL-11.5, SQLite-3.29.0, 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:

    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 '515 d'                                     \
        -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-4.92.1 &&
    install -v -m644 doc/* /usr/share/doc/exim-4.92.1 &&

    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-5.3.28.

`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 connections. 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-4.92.1/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-4.92.1/doc/html/spec_html/ch45.html.

To use a backend database other than Berkeley DB, see the instructions at http://exim.org/exim-html-4.92.1/doc/html/spec_html/ch04.html#SECTdb.

For SSL functionality, see the instructions at http://exim.org/exim-html-4.92.1/doc/html/spec_html/ch04.html#SECTinctlsssl and http://exim.org/exim-html-4.92.1/doc/html/spec_html/ch42.html.

For tcpwrappers functionality, see the instructions at http://exim.org/exim-html-4.92.1/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-4.92.1/doc/html/spec_html/index.html.

For information about linking Linux-PAM, refer to the instructions http://exim.org/exim-html-4.92.1/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-4.92.1/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-4.92.1/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-4.92.1/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 sticky 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

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.

### Systemd Unit

To automatically start exim at boot, install the `exim.service` unit included in the blfs-systemd-units-20180105 package.

    make install-exim

## Contents

Installed Programs: exicyclog, exigrep, exim, exim-4.92.1-5, 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-4.92.1 and /var/spool/exim

### Short Descriptions

exicyclog | cycles Exim log files.
exigrep | searches Exim log files.
exim | is a symlink to the exim-4.92.1-5 MTA daemon.
exim-4.92.1-5 | 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 2019-08-23 15:27:39 -0700

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