E-mail Delivery Delay in java.net

by Kohsuke Kawaguchi

What's this?

This system monitors the latency of e-mail delivery in java.net every 15 minutes, and plots that in a chart. The delay is measured in minutes. It gives you the historical trend of the delay, as well as the estimate of the likely delay if you send out an e-mail now.


Since mid-2005, we are starting to observe a large latency in the java.net e-mail delivery. For example, when someone commits a change in CVS, the delivery of the change notification e-mail gets delayed. When you post to a mailing list, the distribution of that e-mail gets delayed.

This monitoring is an attempt to better understand the problem, and to reduce the impact it causes to our projects.

Method of Measurement

This system sends out an e-mail from kohsuke.sfbay inside Sun firewall. The e-mail goes through a Sun mail server, then java.nte mail server, comes back to a Sun mail server, then finally to kohsuke.sfbay itself. The 'latency' measured here is the time it takes for an e-mail to complete this whole journey.

Therefore, it is not the exact delay in java.net; it includes all the latencies in Sun mail servers. (Note that in our experience Sun mail servers have minimal latency, usually in the order of seconds.)