Preliminary note ================ OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with some additional standard extensions. It allows ordinary machines to exchange e-mails with other systems speaking the SMTP protocol. OpenSMTPD runs on top of the OpenBSD operating system but also has a portable version that can build and run on several systems, including: * Linux * FreeBSD * NetBSD * DragonFly For more information: http://www.opensmtpd.org/portable.html People interested about OpenSMTPD are encouraged to subscribe to our mailing list: http://www.opensmtpd.org/list.html and to join the IRC channel: #OpenSMTPD @ irc.freenode.net Also note that we have a wiki at https://github.com/OpenSMTPD/OpenSMTPD/wiki that you are encouraged to contribute to. Cheers! How to build, configure and use Portable OpenSMTPD ================================================== Dependencies ------------ Portable OpenSMTPD relies on: * autoconf (http://www.gnu.org/software/autoconf/) * automake (http://www.gnu.org/software/automake/) * bison (http://www.gnu.org/software/bison/) or byacc (http://invisible-island.net/byacc/byacc.html) * libevent (http://libevent.org/) * libtool (http://www.gnu.org/software/libtool/) * libressl (https://www.libressl.org/) * libasr (https://opensmtpd.org/archives/libasr-1.0.2.tar.gz) Get the source -------------- git clone -b portable git://github.com/OpenSMTPD/OpenSMTPD.git opensmtpd Build ----- cd opensmtpd* ./bootstrap # Only if you build from git sources ./configure make sudo make install # Special notes for FreeBSD/DragonFlyBSD/Mac OS X: Please launch configure with special directive about libevent and libasr directory: # FreeBSD / DragonFlyBSD: ./configure --with-libasr=/usr/local # Mac OS X: ./configure --with-libevent=/opt/local --with-libasr=/opt/local Install ------- sudo make install Setup historical interface ------- OpenSMTPD provides a single utility `smtpctl` to control the daemon and the local submission subsystem. To accomodate systems that require historical interfaces such as `sendmail`, `newaliases` or `makemap`, the `smtpctl` utility can operate in compatibility mode if called with the historical name. On mailwrapper-enabled systems, this is achieved by editing /etc/mailer.conf and adding the following lines: sendmail /usr/sbin/smtpctl send-mail /usr/sbin/smtpctl mailq /usr/sbin/smtpctl makemap /usr/sbin/smtpctl newaliases /usr/sbin/smtpctl Whereas on systems that don't provide mailwrapper, it can be achieved by setting the appropriate symbolic links: ln -s /usr/sbin/smtpctl sendmail ln -s /usr/sbin/smtpctl send-mail ln -s /usr/sbin/smtpctl mailq ln -s /usr/sbin/smtpctl makemap ln -s /usr/sbin/smtpctl newaliases The OpenSMTPD project leaves it up to the package maintainers to setup the links in their packages as it is very hard for us to accomodate all systems with the prefered method in a clean way. Configure /etc/smtpd.conf ------------------------- Please have a look at the complete format description of smtpd.conf configuration file (https://man.openbsd.org/smtpd.conf) Add OpenSMTPD users ------------------- To operate, OpenSMTPD requires at least one user, by default _smtpd; and preferably two users, by default _smtpd and _smtpq. Using two users instead of one will increase security by a large factor so... if you want to voluntarily reduce security or you have absolute more faith in our code than we do, by all means use one. The instructions below assume the default users however, the configure script allows overriding these using the options: --with-user-smtpd, --with-user-queue, and --with-group-queue. # NetBSD, Linux (Debian, Arch Linux, ...) mkdir /var/empty useradd -c "SMTP Daemon" -d /var/empty -s /sbin/nologin _smtpd useradd -c "SMTPD Queue" -d /var/empty -s /sbin/nologin _smtpq # DragonFlyBSD, FreeBSD pw useradd _smtpd -c "SMTP Daemon" -d /var/empty -s /sbin/nologin pw useradd _smtpq -c "SMTPD Queue" -d /var/empty -s /sbin/nologin # Mac OS X First we need a group with an unused GID below 500, list the current ones used: /usr/bin/dscl . -list /Groups PrimaryGroupID | sort -n -k2,2 Add a group - here we have picked 444: /usr/bin/sudo /usr/bin/dscl . -create /Groups/_smtpd PrimaryGroupID 444 Then the user. Again we need an unused UID below 500, list the current ones used: /usr/bin/dscl . -list /Users UniqueID | sort -n -k2,2 Add a user - here we have picked 444: /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd UniqueID 444 /usr/bin/sudo /usr/bin/dscl . -delete /Users/_smtpd AuthenticationAuthority /usr/bin/sudo /usr/bin/dscl . -delete /Users/_smtpd PasswordPolicyOptions /usr/bin/sudo /usr/bin/dscl . -delete /Users/_smtpd dsAttrTypeNative:KerberosKeys /usr/bin/sudo /usr/bin/dscl . -delete /Users/_smtpd dsAttrTypeNative:ShadowHashData /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd RealName "SMTP Daemon" /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd Password "*" /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd PrimaryGroupID 444 /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd NFSHomeDirectory /var/empty /usr/bin/sudo /usr/bin/dscl . -create /Users/_smtpd UserShell /usr/bin/false repeat for the _smtpq user. Launch smtpd ------------ First, kill any running sendmail/exim/qmail/postfix or other. Then: smtpd or in debug and verbose mode smtpd -dv # Docker version OpenSMTPD provides a convenient docker file for getting started quickly. However, there are a few minor quirks to know about. For ease of use, all configuration files live in '/etc/mail'. This means the two files to modify are: /etc/mail/smtpd.conf /etc/mail/mailname Also, local deliveries are disabled by default. The nature of Docker makes interacting with local users a bit tricky, and requires a user to know the ins and outs of Docker. To run the Docker version, create a '/etc/mail' directory, and add your own smtpd.conf file there. Next, run: ``` docker run --name smtpd_server -p 25:25 -v /etc/mail:/etc/mail emperorarthur/opensmtpd ```