Droo-Labs

the perspicacious ramblings of droo

HowTo Setup Authenticated Postfix

I recently had the experience of setting up Postfix. It works really well, in my opinion; however, setting it up wasn’t the simplest for what I wanted. But, at least it was simpler than sendmail :-)

Reading through several articles on the Internet, everyone was giving steps on how to setup postfix to handle e-mail for any FQDN (Fully-Qualified Domain Name). Well, we don’t want to be handling someone else’s e-mail, so we decided to set it up with authentication. All of the guides on setting up Postfix with SASL authentication are great and all; however, they don’t address the issue of, what if you want to receive mail as well. That’s a simple fix, but moreover, what if you have a service like mailman running? Mailman isn’t easily configured to authenticate against the SMTP server to send mail. So, the following are the configurations that I’ve come up with to solve all of these problems:

For the file /etc/postfix/main.cf

queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
myhostname = hostname.domain.tld
mydomain = domain.tld
myorigin = $mydomain
inet_interfaces = all
inet_protocols = all
mydestination = $myhostname, localhost.$mydomain, localhost, localhost.localdomain, $mydomain
unknown_local_recipient_reject_code = 550
mynetworks = 192.168.0.0/24, 127.0.0.1/32
relay_domains = $mydestination
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
broken_sasl_auth_clients = yes
alias_maps = hash:/etc/aliases, hash:/etc/mailman/aliases
alias_database = hash:/etc/aliases
recipient_delimiter = +
debug_peer_level = 2
debugger_command =
         PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
         ddd $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.6.5/samples
readme_directory = /usr/share/doc/postfix-2.6.5/README_FILES

Now keep in mind, your values for some of the above WILL be different. This configuration is on a machine that’s running mailman as well (thus the /etc/mailman/aliases file).

And lastly, for SASL auth, edit the file: /usr/lib64/sasl2/smtpd.conf

pwcheck_method: saslauthd
mech_list: plain login

Your lib64 directory may just be lib, depending on the architecture of your box. All of these edits were made a 64-bit Fedora 12 machine, but they should work for every machine.

And last note. After all of the edits have been made, make sure to restart postfix and restart saslauthd with the following:

/etc/init.d/postfix restart
/etc/init.d/saslauthd restart

For questions on what some of the postfix settings mean, you can check out one of the following:

postconf man-page by running “man postconf” or visit http://www.postfix.org/postconf.5.html

Postfix Documentation at: http://www.postfix.org/documentation.html

Postfix HowTo’s at: http://www.postfix.org/docs.html

Postfix is definition the easiest MTA I’ve ever had the pleasure of working with, as far as configuration goes. I hope this helps :-)

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