Oh cool! That rings a bell! :)
I wrote and am operating a similar service at http://remaildr.com
The implementation is open source at https://github.com/Pluies/remaildr/
The main issue I've had with this side project is the availability that wasn't so great (as monitoring was conspicuously absent from the start and I never got around to actually setting it up, but I've got plans for it!) and it was eventually caught by spam due to Spamassassin misconfiguration on my part.
So I hope you have a good process for handling spam, and fingers crossed your code crashes less often than mine :)
