ways of integrating into Thunderbird

http://sourceforge.net/apps/mediawiki/attachreminder/index.php?title=Main_Page

it seems to me that we could repurpose this plug-in as a way of adding proof of 
work stamps. One potential problem might be the time it takes to generate stamps 
and how long we get in the user's way.

Have folks seen better Thunderbird plug-ins we could repurpose?