Many of you by now have heard, privately at least, that MailChannels has developed an email system load testing service. We developed this service initially for ourselves (to test the scalability of Traffic Control), but have recently started offering it to existing and potential customers.
The load testing tool works by spawning up to 100 server instances with Amazon's Electric Compute Cloud (EC2), each instance of which spawns hundreds or thousands or SMTP clients which throw millions upon millions of SMTP connections at a target mail server. The clients can be configured to behave in a number of ways, which allows us to simulate real-world email traffic patterns.
We can generate truly earth-shattering email system loads with this service.
For example, when we threw our traffic at a Postfix/SpamAssassin installation (delivering to /dev/null) running on an eight-core box with 15GB of RAM, Postfix quickly queued up about an hour's worth of email. The load average on the machine was 117.5, with 6GB of RAM being eaten up by the Postfix and SpamAssassin processes.
To find out how your mail server scales, please fill in our inquiry form to set up a load test.