Follow up: An Open Source Perspective on Commercial MTAs | Port25 Solutions, Inc.
Fred Tabsharani

By port25admin

Follow up: An Open Source Perspective on Commercial MTAs

It’s always refreshing to obtain a different perspective, especially from the open-source community regarding email sending infrastructure.  For those who are currently utilizing an open-source product, we thought this feedback from one of our constituents would be valuable for decision makers.

From feedback regarding our Open Source vs. Commercial MTA Whitepaper released in January, an advocate of open source sending software,  Mr. Matt Sergeant, provided his own viewpoints between  the tangible differences of open source and commercial MTA software.  Based on these perspecitves we’re updating our latest Whitepaper to give readers and decision makers a more objective thread on why commerical MTAs are such a critical investment for enterprise level sending environments.   Below is Matt’s perspective:

Things commercial MTAs offer that (most) open source MTAs don’t:

  • Cluster support
  • Monitoring (including cluster monitoring)
  • Bounce handling
  • Per recipient domain settings
  • VirtualMTA Technology
  • Email Encryption

 Cluster Support

Commercial MTAs usually have some form of built-in support for centralised management of a cluster of servers. This can be as basic as shared configuration data, or as complex as full control of every machine in the cluster from a centralised management console, shared information between instances of current connection counts to recipient domains, and cluster-wide monitoring.   This is only one benefit for the new PowerMTA Management Console introduced this past year by Port25.


Most commercial MTAs have built-in monitoring support. To monitor open source MTAs you often need to install some external monitoring tool (such as Nagios) and rely on whatever support is built into that tool for monitoring your mail server.   Alternatively you end up writing your own monitoring software, or plugins for your monitoring software of choice. This becomes particularly tricky when you have multiple servers, and need to be able to monitor as both an aggregate and be able to “drill-down” into individual servers.

Bounce Handling

Modern commercial MTAs have sophisticated algorithms that they have built up over years of experience for managing bounces. Because the SMTP RFCs are often unclear on giving reasons why a mail may have bounced, these commercial MTAs have built up techniques for understanding responses from different types of recipient MTAs, providing the administrator of the commercial MTA with the appropriate tools for dealing with bounces in a manner which is appropriate given the information at hand.

Per Recipient Domain Settings

While some open source MTAs have some level of per-domain settings for outbound email, this is often rather complex to code or doesn’t exist at all. Commercial MTAs were mostly borne from the need for large senders, and so having flexible configuration on a per-recipient domain basis is a basic requirement.

Email Encryption

Commercial MTAs now have the ability to encrypt outbound email with SMTP over TLS.  Both the receiver and the sender have to have email encryption enabled.  As we move towards email encryption as a standard Port25 has optimized performance optimization in it’s latest version v4.5.



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