Postfix

The Postfix MTA is a sendmail alternative created by Wietse Venema that is designed to be faster, much easier to administer and more secure than sendmail. It is said that in achieving these design goals, it is less flexible than sendmail. Postfix generally works without much input by the system administrator and can drop right in and transparently replace a sendmail installation.

How to get it
Install Postfix as described at Installing Software. If you need a modified Postfix, download the source code, then compile, link and install it. For downloading, visit http://www.postfix.org. Building is described at Compilation from source.

How to use it
To see if your Postfix is configured properly, send yourself a mail: $ sendmail -t me@home.org FROM:me@server.org TO:me@home.org SUBJECT:test this is a sendmail test Stop your input by typing CTRL_D. In this case, me@home.org is your e-mail-address.


 * detect if your server is used as a spambot

Deliver all mail to procmail
To make your postfix MTA deliver all mail to procmail for further processing, mailbox_command = /usr/bin/procmail /etc/init.d/postfix restart
 * make sure procmail is installed
 * enter in /etc/postfix/main.cf a line like:
 * restart your postfix

Catch-all e-Mail addresses
Imagine you have a domain example.org and want all mails for this domain in a mailbox, so, no more "user does not exist" replies to senders. Then you configure a catch-all for this domain.

Go to webmin->servers->postfix->virtual domain Enter a Domain mapping lookup table. Click on "new" and map, e.g. example.org to exampleuser.

Allow sending from a MUA
Imagine you have a mail server running postfix and you want to use it in a MUA (e.g. kmail) as smtp server. This will most likely fail with an error message like Relay access denied And you will have no chance to authenticate. To change this, add smtpd_sasl_auth_enable=yes to /etc/postfix/main.cf, and outcomment all lines starting with tlsmgr in /etc/postfix/master.conf.

Working with the Mail Queue
The outgoing mail queue is often stuck, so here's how you deal with that:

To watch your outgoing mail queue, use the command mailq

To read your outgoing mail queue, use webmin which has an own module for Postfix.

To flush your mail queue, use postqueue -f

To delete a mail from your mail queue, find out its mail-id by running mailq then delete the mail by running postsuper -d mail-id