Recipe 20.3. Building a POP3 Mail Server on Debian

20.3.1 Problem

You want to run a Postfix/Courier POP3 server on Debian, and you need to know the Debian way of doing this.

20.3.2 Solution

Debian automates most of the process. Install or upgrade famd, OpenSSL, and Postfix:

# apt-get install famd openssl postfix postfix-doc postfix-tls

Debian will walk you through a basic Postfix configuration and start it up. Next, back up /etc/postfix/main.cf:

# cp /etc/postfix/main.cf  /etc/postfix/main.cf-old

Erase everything in the original, and copy in these lines. Be sure to enter filepaths and host/domain names appropriate for your system:

command_directory = /usr/sbin mail_owner = postfix default_privs = nobody # enter your domain name here mydomain = tuxcomputing.com # enter your own fully qualified domain name here myhostname = windbag.tuxcomputing.com myorigin = $mydomain     alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases inet_interfaces = all mydestination = $myhostname, localhost.$mydomain $mydomain mynetworks_style = subnet     # very important! Courier must have maildirs, not mbox home_mailbox = Maildir/ mail_spool_directory = /var/mail mtpd_banner = $myhostname ESMTP $mail_name mailbox_size_limit = 0 recipient_delimiter = +

Create a mail alias for root in /etc/aliases:

# See man 5 aliases for format root:[e-mail] postmaster:root

Then create the alias database:

# newaliases

Run the built-in syntax checker:

# postfix check

Next, restart Postfix:

# postfix reload postfix/postfix-script: refreshing the Postfix mail system

Now install Courier:

# apt-get install courier-authdaemon courier-base courier-doc courier-pop courier-pop-ssl courier-ssl

Debian will automatically generate the keys and start the Courier daemons. However, you should edit /etc/courier/pop3d.cnf, and manually generate a new certificate with the updated data. Recipe Recipe 20.2 tells how to do this.

20.3.3 Discussion

postfix reload is the fastest, least intrusive way to activate changes to main.cf. Use it when the system is under load and you don't want to disrupt service.

Always check the Debian packages search page, at http://packages.debian.org. Debian has its own package naming conventions and tends to split up packages into many small components.

20.3.4 See Also

• Recipe 20.2, for manually generating a Courier certificate

• The Debian packages search page (http://packages.debian.org)

• Postfix Basic Configuration (/usr/share/doc/postfix/html/basic.html)

• Local Courier documentation (/usr/share/doc/courier-doc)

• Recipe 20.4