Background
I started rewriting my pet project from scratch in .NET 2.0 last summer, and I'm proud to announce version 2.0 of E = m c² (or should I say E = m c2.0) is now finally all polished and ready! I'm actually pretty happy with it (and using it all day every day), so to make it stand out a bit more, I've created a separate site for it at http://jelle.druyts.net/emc/. That's where you can find all the information and download this free tool.
By the way, E = m c² (apart from a silly little formula relating an object's mass to its energy content) stands for Extensible Message Checker 2.0, because it's a tool that can check for messages (in the broadest sense) and, well, it's extensible (fully driven by plugins that you can easily create yourself).
Introduction
E = m c² is a utility that can check various sources for messages, then filter and redistribute them.
A typical example is checking your mailbox and showing you a popup window if there are new messages, but it goes far beyond that since it's fully extensible using plugins. For example, you can check RSS files for new blog posts, monitor when a server comes online or goes offline, play a soundfile when new messages arrive, send a summary email, run a program, write to an RSS file, ...
Basically, you can make E = m c² do all you can think of! And it can do your laundry too (Pro version only)!

Features
Runtime
- Fully extensible using plugins.
- Settings are saved to an xml file so you can easily edit and copy it.
- Certain settings can be encrypted if needed by plugins (e.g. passwords).
- Runs in the background, it's basically just an icon in the system notification area.
- Easy to install, set up and remove (if you could live without it).
Plugins
- Check POP3 and IMAP email.
- Check Outlook Web Access (OWA) and Outlook Mobile Access (OMA) email.
- Check RSS 2.0 feeds.
- Monitor the file system, i.e. get notified when directories or files change.
- Monitor server status (by ping or by checking a url).
- Filter messages by content.
- Write new messages to a text file or an RSS 2.0 feed.
- Show a desktop alert, a message box or a rich message viewer when messages arrive.
- Run a program, change the desktop background, play a sound or send an email when messages arrive.
- ...And you can easily write your own!
Alright, enough already, where is it?
You can find all information, screenshots, downloads, and even tutorials on writing plugins at the dedicated website: http://jelle.druyts.net/emc/. Did I mention it's free?