zlacker

>>todsac+(OP)
I wrote my own email archiving software. The hardest part was dealing with all the weird edge cases in my 20+ year collection of .eml files. For being so simple conceptually, email is surprisingly complicated.

>>thedan+al
I wrote a console-based mail client, which was 25% C++ and 75% Lua for defining the UI and the processing.

It never got too popular, but I had users for a few years and I can honestly say MIME was the bane of my life for most of those years.