User:Paul/sandbox/Fully-functional mail server with Postfix, Dovecot and MySQL

This article covers setting up a full mail server on a UNPM server. The mail server will support SMTP, POP3 and IMAP, secure connection for clients, secure connection available for other mail servers, serving mail for multiple domains, and spam control.

Sending and receiving email is more complicated than most people realize. Novice and enthusiast admins may have difficulty figuring out what packages to install, and even after that it can seem nearly impossible to get everything working. This article greatly eases many of those difficulties, but running a mail server is not a trivial matter and will add additional workload for the admin.

The majority of the configuration settings and explanations in this article come from the Ex Ratione blog post A Mailserver on Ubuntu 12.04: Postfix, Dovecot, MySQL under the CC BY 3.0 license. This article varies from the original by explaining how to install to a server with nginx.

Note that this mail server will not work with servers on hosts who block access to ports, such as port 25.

Nearly all of the commands in this article require root:

username@servername:~$ sudo /bin/bash

Hostname

The hostname of the server must be mail.example.com.

root@servername:~# nano /etc/hostname

The contents of the file must be:

mail.example.com

root@servername:~# nano /etc/hosts

The first line must contain the hostname:

127.0.0.1 mail.example.com localhost

Note that if the server is a VPS or cloud server, if the hypervisor is rebooted, these settings may be reverted to the original settings the server was configured with, which will cause the mail functions of the server to stop working without any notification. The best way to circumvent this issue is to create the server such that these settings are already in place, which may be possible by naming the server mail.example.com when creating it in the ISP's dashboard, or renaming it, if the option to do so is available.

SSL/TLS certificates

One thing to note is that to avoid SSL/TLS warnings from email clients, the certificate for the domain used will have to include the mail subdomain (e.g. mail.example.com). In the world of mail clients, the warnings tend to be much softer and less obtrusive than browser warnings. However, if even this is to be avoided, the solutions are to either pay for a certificate ($59.90/year from StartSSL) to add additional subdomains or use a domain exclusively for the mail domain (e.g., StartSSL certificate for example.com and mail.example.com).

DNS entries

The mail server can manage many domains, even multiple domains using mail as the subdomain, but is generally easiest to use one domain as the mail server (e.g. mail.example.com manages mail for mail.example2.com) domain that will be used in all MX records. This is a common practice among many ISPs and it is very rare that anyone ever notices since the only way to discover this information is to run a DNS query.

For the mail server domain, create A/AAAA records pointing to mail.example.com.

Install packages

The following packages will be required for this setup (note the ^ which is used to install meta-packages):

root@servername:~# aptitude install php-xml-parser
root@servername:~# apt-get install mail-server^

During the mail-server set up, select 'Internet site'. When asked for the hostname, use mail.example.com, although this setting will not really apply to the final setup since the mail server will be using a MySQL database for domain management.

root@servername:~# aptitude install postfix-mysql dovecot-mysql dovecot-imapd postgrey 
root@servername:~# aptitude install amavis clamav clamav-daemon spamassassin
root@servername:~# aptitude install php5-imap
root@servername:~# aptitude install libnet-dns-perl pyzor razor
root@servername:~# aptitude install arj cabextract nomarch pax

Set up the database

This database will be used to store all of the information for user accounts and mail domains.

root@servername:~# create database mail;
root@servername:~# grant all on mail.* to 'mail'@'localhost' identified by 'mailpassword';

Install Postfix Admin and the database schema

Postfix Admin is a PHP based application that handles Postfix style virtual domains and users that are stored in the database. The application has a user-friendly web-based GUI.

root@servername:~# wget http://downloads.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-2.3.7/postfixadmin-2.3.7.tar.gz
root@servername:~# tar -xvf postfixadmin-2.3.7.tar.gz

root@servername:~#

Configure nginx

It is important to understand that nginx and other mail server configuration settings are separate, except for the components that may be served by nginx, such as Postfix Admin and Roundcube.

Depending on the subdomain being used for the mail server, the web packages may be served from mail.example.com or www.example.com/mail

External links

How to send one billion email messages per month