Postfix Configuration Explained

Downloading and installing as many applications, utilities, packages, etc. as possible can be done by following a few basic steps that take only a few seconds to complete. But is that enough for successfully using an application? The answer to this question is, “No.” The reason is that the successful working of an application entirely depends upon its sound configurations. If you manage to configure all the important settings correctly, then you should not face any issues while using that application.

Many users hesitate to configure these settings on their own due to a fear of messing up. However, at the very least, computer users should know how to deal with basic configurations of the most commonly used utilities. This includes a sound knowledge of all the default settings, so that if something has been chosen by default by the OS, then the user can understand the reason for this default choice. This knowledge proves to be helpful in the long run when changing the default settings becomes necessary. This article will discuss Postfix Basic Configurations performed during the Postfix installation process.

Important Postfix Configurations

The basic Postfix configurations are listed in the following sections.

Mail Server Configurations

Five different options are provided to the user for the mail server configurations, listed below:

No Configuration

As the name implies, you do not choose any particular configuration in this option; rather, it will default to whatever the current mail server configuration is, and this option will leave it unchanged.

Internet Site

This option is chosen when you want to send and receive emails using the Simple Mail Transfer Protocol (SMTP).

Internet with Smart Host

For this option, emails are received using SMTP, but they are sent using the smart host.

Satellite System

In this case, the emails are sent to a smart host before their delivery.

Local Only

For this option, emails are only delivered to the local users and there is no network present at all.

Out of these five options, the Internet Site option is recommended.

System Mail Name

This setting allows you to choose your System Mail Name or a Fully Qualified Domain Name (FQDN) to be used for sending and receiving emails via Postfix. There is no restriction on this configuration as such and you can choose any name of your choice. For example,,, etc.

Root and Postmaster Mail Recipient

This setting allows you to select the name of your user account. You are also allowed to keep it the same as your primary username on your computer system. For example, Alice@, Bob@, etc.

Domains List

The domains list configuration enables you to add all the domains from which your Postfix mail server is capable of accepting emails. A default list of all the relevant domains is provided by your system during Postfix installation, but you can add more domains of your choice, separated by commas.

Force Synchronous Updates on Mail Queue

If this setting is enabled during installation of Postfix, then your emails will get processed very slowly. Therefore, to speed up this process, it is highly recommended to disable this setting.

Local Networks

This setting specifies all the local networks to which your Postfix mail server is capable of relaying emails. By default, your system will present you with just the local hosts. However, you can always add more local networks of your choice, according to your requirements.

Mailbox Size Limit

This is the size of the messages in bytes that your mailbox is capable of accepting. You can either have a custom defined size, or you can keep it to zero, which means that you do not want to have any restriction on the message size. The default value for this configuration is zero and it is also the recommended value.

Local Address Extension Character

This setting allows you to define a character to be be used for the local address extension. Here, the default value of this setting is the “+” character, but you can change this to any character of your choice.

Internet Protocol

The last configuration is deciding the Internet Protocol to be used for sending and receiving emails. There are three options provided for this configuration, i.e., IPv4, IPv6, and All (which means both IPv4 and IPv6). The default value, in this case, is “All,” and it is highly recommended that you stick with this value so that your Postfix mail server is capable of using both of these protocols, as per the requirements.


By reading the sections above, which cover the most important configurations of Postfix, you will be in a good position to understand other important configurations. After reading this article, you should now be able to now configure the basics of your Postfix mail server with ease.

About the author

Karim Buzdar

Karim Buzdar

Karim Buzdar holds a degree in telecommunication engineering and holds several sysadmin certifications. As an IT engineer and technical author, he writes for various web sites. You can reach Karim on LinkedIn.