MSH Multi-Threaded Parallel processing for Interspire Email Marketer


What is it?

MSH is a multi-threaded, parallel processing addon for Interspire Email Marketer(IEM) which helps improve it's sending speed.

While IEM is a featureful list manager, it's mail sending speed is notoriously low for most bulk sending purposes. On the contrary, popular mail transfer agent(MTA), such as Postfix, Exim, Sendmail, Powermta etc. are actually capable of processing mails at much higher rates than IEM can deliver them to. MSH add-on covers up the lag between processing speeds of your MTA and the list manager by adding parallel processing capabilities to IEM.

How good is it?

With the help of MSH add-on, IEM can easily achieve an speed-up of at least 5 times, while how far can you go is only limited by hardware resource.

Interspire multi-threaded addon benchmark graph Figure: Result of a benchmark showing how performance of Interspire Email Marketer changes with different number of threads/processes active using MSH addon. The first bar represents vanilla Interspire with just a single thread. Read the detailed benchmark here in our release announcement.

How does it work?

IEM is only slow because it's a traditional single-threaded, single-process PHP application which, by design, can not take advantage of modern computers. The way MSH addon works is by transforming it into a modern day application, capable of leveraging multi-core processors and high speed storage media with the help of parallel processing technique.

To get a general idea of the internals, please see the section - parallel processing explained. Technically interested readers might check out the technical section.

Is it special from other multi-threaded addons?

Yes it is. MSH is not a clever database hack to simulate multi-processing, behind it is a clean and elegant technology that sets it apart from others. Reasons you might consider MSH for -

  • Superfast, highly scalable and reliable sending.
  • Multiple simultaneous campaign processing.
  • Fine tuning the sending process for optimal performance.
  • Drop in performance gains. Just pause your campaign, install MSH and resume.
  • Full source code for your tweaking needs.
  • Free first time installation and lifetime free updates.

Also, our marketing partners sell the add-on with different brandings. If the add-on you are considering is from one of these sites, you are actually buying MSH. You are more than welcome to make a purchase through them.

"Parallel Processing" explained ...

Imagine an office worker who is overloaded with her desk full of files. She takes the files one by one, reviews them and then places them in a seperate pile so that her personal assistent can pick it up. Her day to day job is not only boring but also painstalkingly slow. Now replace the office worker with Interspire Email Marketer and her office assistent with your MTA of choice - you get the picture of how IEM processes campaigns and why it acts so slow while processing large campaigns.

Let's imagine an alternative situation where our ordinary worker becomes extra-ordinary and learns 'dark magic'! She magically makes five clone copies of herself along with the desk, places them in her office and then distributes the pile of files to all of them. While she is just handing over the files, her clones are busy processing them. This time, our clever worker will complete her works in one fifth of the previous situation. Interestingly, her office assistent will have an unusually busy day too. Finally, replace 'dark magic' with MSH add-on!

Have questions?

If you have more questions regarding the addon please feel free to consult the forum.

Price Plan

MSH addon is distributed under a "perpetual, installation domain restricted" license, which grants full permission to "source modifications" for internal use. Single domain license is priced at 400 USD only. Every additional purchase is subject to +15% discount upto a maximum discount of 45%.

Every purchase comes with -

  • MSH add-on with installation and configuration documentation.
  • Commented, unencrypted, unobfuscated source code.
  • Free of charge first time installation(on demand).
  • Lifetime update support.

System Requirements

  • Interspire Email Marketer 6.1.x.(from 6.1.0 to 6.1.6)
  • PHP Command Line Interface(CLI) 5.3 or above.
  • PHP sockets extension must be available and enabled in the CLI.
  • PHP program execution functions must be enabled in the CLI.
* GNU/Linux and Windows NT family operating systems are officially tested and supported with MSH. But it is likely to work with any operating system where PHP sockets extension is properly implemented (has no platform specific bugs).



MSH add-on started life as an in-house software for one of our clients. First release of MSH was only compatible with "unix family" operating systems, as it used some unix-only PHP extensions for process control and inter process communication.

After the release of IEM 6.1.1, MSH became unreliable and broken due to some unspecified behavior of PHP MySQL extension when forked. This prompted us to do a complete rewrite with different strategy.

MSH v2 (swiftrunner) solves all the problems it's predecessor had and is written around PHP extensions available in all platforms. As a result, for the first time, MSH is also capable of running in windows servers, besides unix family ones.


MSH is built around "multi processing library", a multi platform ,shared nothing, multi processing framework inspired by Python multiprocessing module(but very different from api level). It uses "proc family functions" for process spawning and "soq" for IPC.

"soq"(pronouced "so-queue") is a robust and reliable, pipe-like message queue on top of PHP sockets, developed by us and distributed under the licensing terms of GNU LGPL. You can find it here in bitbucket.