Choosing MTA for mail server – PMTA vs Postfix – Choosing MTA

MTA – Mail Transfer Agent, is a program that sends messages from one server to another. From this article you will learn which software to choose.


PowerMTA is a professional (paid) software for organizing your own mail server. It is used by leading Western services that send out billions of emails every month, such as GetResponse, Mailchimp, iContact and others.

In order for you to achieve good deliverability, you have to configure the pmta config file, then you have to work on your domain and ip reputation.

How PMTA works

The pmta configuration has it’s own rules: mailing speed, number of threads, how many emails per thread, and many others.
Use special console commands to to administrate pmta via server’s terminal.
The list of these rules is a part of so called macro, which is separate for each mailer. Besides, each mailer’s macro also contains the rules of switching to Backoff mode, as well as the rules of Backoff mode itself. PMTA analyzes recipients’ email domains and distributes emails according to mailer macros. After that, it sends the email according to the rules that are specified for each mailer in its macro.


Postfix is an open-source (free) mail server that is most often used as a mail server for web sites. Once installed, Postfix is ready to perform it’s primary task of handling mail messages, but it doe’s not have an authorization subsystem. That is, anyone can connect to the mail server and send or receive messages for any mailbox. Dovecot is a special plugin that adds authorization functionality to Postfix. You can install postfix on your server by following this guide.

How postfix works

Postfix consists of several small, collaborative programs that send network messages, receive messages, perform local mail delivery and other activities. Communication between the programs is done using Unix sockets or FIFO algorithms. The architecture is different from Sendmail, where all the work has to be done by one big program.


Exim – is a is a simple SMTP server that works on computers running Unix-like operating systems. It is free software that functions as a highly flexible mail server. It is highly flexible and can be used to perform a variety of tasks, such as creating virtual domains or expanding mailing lists. Not all mail servers have this feature.

How exim works

Exim 4 is designed for systems with a permanent network connection, so it does not have complex queuing mechanisms through which all messages must go. In the default setting, Exim tries to deliver the message immediately. If there is a heavy load on the server, immediate delivery mode can be temporarily turned off.

Which MTA is better?

It depends on your needs.

If you want easy setup and functionality, use EXIM.
If you need reliable mail on your domain, for example, but you are not going to send mail in large quantities, then choose the free Postfix.
And if you are going to send lots of mail, or even set up your own newsletter service, and have a very large subscriber base, PMTA will do the job.

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