If you are a sysadmin or developer or similar you probably get a bunch of emails from systems telling you they are doing just fine. You probably have mail rules to shove these off into some folder you never look at so you can get on with life. If one should happen to not turn up, that would be kind of interesting, but there is no email rule you can make to alert you about an email that didn’t happen. Over the last couple of weeks I have been building a system to fix that http://exceptionalemails.com. You basically shove all the emails you get at a set of special email addresses, one for each type of regular email, and set up rules saying what you expect to happen. You then get on with your life, and if an email fails to happen, or perhaps contains the wrong words (fail/error/out of disk space/etc.) then and only then we will send you an email – you only need to see the exceptions.
This is the form to set up the rules for an alert, so in this example I would set my fileserver backup schedule to email email@example.com when it is done (or leave it emailing me, and set up a rule to put the mail in a folder of my email and forward the mail to firstname.lastname@example.org)
This was my first project using MongoDB as a back end and I have been really impressed by it, I have a background in NoSQL and it all made sense to me in terms of performance expectations and optimisations. I load tested it with a million emails and it was still really fast. It is running on Ubuntu server, with a user interface is written in PHP. The back end jobs that receive emails and check for alerts going overdue are written in Python.
I would be really interested in any feedback on the site, I have some plans for improving the analysis of past emails with sparklines so you can see when failures happened, and maybe fluctuations of arrival times of emails. Any other suggestions would be welcome. There is an outside chance that I might write a JuJu charm for it – and probably do a bit of a refactoring of the code to make deployment easier. One of the reasons for choosing MongoDB at the back end and a separate process to receive the emails was to allow it to scale horizontally across a bunch of servers. Based on my load testing I couldn’t hammer it hard enough to slow things down noticeably so I am not sure my grand clustering plans are going to be required.
The code is on Github, under AGPL3 and I am tracking issues there.