Ah, the unsung heroes who do their job so well, that nobody notices... In this case I'm speaking (singing?!) of Squirrelmail (and its multitude of (largely) useful plugins). I've been using Squirrelmail (oops, sorry, I keep forgetting)... we have been using Squirrelmail now for well over three years and pretty much from the start it was something simple and useful and just worked[tm].

It's been a selling-point for quite a few of my hosting customers over time (well, along with the virtues of IMAP in general and Cyrus in particular) but only today did I finally venture into the plugins to enhance the experience. In the end I installed just three: Quota support, New User Wizard and (most importantly) the insanely useful avelsieve.

Now all our customers can enjoy serverside filtering with (relatively) easily clickable rules. The screenshot shows the perhaps most useful of all: discarding mail according to its X-Spam-Score (provided by SpamAssassin).

I spent well over five hours exploring and testing various other plugins and the best usages for the ones I decided to stick with, but it was a thoroughly enjoyable geek experience... you know... it works!

Update: Actually the rule shown in screenshot below is incorrect - it's comparing the X-Spam-Status header, not X-Spam-Score. That header is conspicioulsy absent from the default setup of avelsieve. However, in order to add it, all it takes is editing avelsieve's config.php (search for '$header').