Postfix is a flexible and easy to configure replacement for sendmail. By following these instructions you can have a complete Postfix installation complete with support for POP, IMAP and vhosts. POP and IMAP will be supplied by Dovecot. This tutorial will be based on Opensolaris 2009.06 with Blastwave.
The first thing to do is to disable sendmail.
# svcadm disable sendmail
Now to install postfix and related packages. Procmail is a powerful mail processing tool that can be configured to do just about anything with a message and the popular spamassassin anti-spam agent.
# pkg install SUNWprocmail # /opt/csw/bin/pkgutil -i CSWspamassassin # /opt/csw/bin/pkgutil -i CSWpostfix
Symlinking to common paths is always convenient when troubleshooting.
# ln -s /etc/opt/csw/postfix /etc/postfix # cp /etc/mail/aliases /etc/postfix
Time to create the users that will own the virtual mailbox storage files. Take note of the UID/GID of these accounts as they're needed in the configuration.
# groupadd virtmail # useradd -g virtmail -s /bin/false -c "Virtual Mail User" virtmail # grep virtmail /etc/group /etc/passwd
Setting up and integrating spamassassin into postfix requires a few things to be done. First we need to create a user/group for spamd to run under and a user/group for the spamfilters to use.
# groupadd spamd # useradd -g spamd -s /bin/false -d /home/spamd -c "Spamassassin User" spamd # grep spamd /etc/group /etc/passwd # groupadd spamfilt # useradd -g spamfilt -d /home/spamfilt -s /bin/false -c "Spam filter User" spamfilt # groupadd spamfilt /etc/group /etc/passwd
Now we need to configure spamassassin. Symlink the spamassassin config directory to an easier to remember location and edit the loval.cf file[;/P:]
# ln -s /opt/csw/etc/spamassassin /etc/spamassassin
An example local.cf
# Rewrite the subject header to start with *****SPAM***** rewrite_header Subject *****SPAM***** # trust mail from this network trusted_networks 192.168.100. # required score to tag mail as spam required_score 5.0 # use bayesian filters built into spamassassin use_bayes 1 # whether or not to feed mail into the bayesian scoring system bayes_auto_learn 1 # path to store bayesian filter information bayes_path /home/spamd/ # permissions to store bayesian filters bayes_file_mode 0666 # whitelist mail from firstname.lastname@example.org whitelist_from email@example.com # whitelist all mail from nospam.com whitelist_from *@nospam.com # blacklist mail from firstname.lastname@example.org blacklist_from email@example.com
Spamassassin needs to be running as a daemon.
# /opt/csw/bin/spamd --daemonize --username spamd --pidfile /home/spamd/spamd.pid
Now create a simple shell script called spamfilt.sh to process the mail through spamassassin and place it in /opt/csw/bin. This is the script that will be called by postfix.
#!/bin/sh /opt/csw/bin/spamc | /opt/csw/sbin/sendmail -i "$@" exit $?
Adjust the permissions of the new script
# chown root:spamfilt /opt/csw/bin/spamfilt.sh # chmod 755 /opt/csw/bin/spamfilt.sh