I've released a new hep tarball that fixes a bugs in the 0.1 version, where messages with long Subject lines and/or IDs would get corrupted. The new also version stores it's messages in maildir directories, which is faster and much less prone to corruption. Also, it uses a slightly different format for the ID numbers it generates for RSS newsfeeds.
This means that, if you're currently using Hep 0.1, you'll lose whatever messages are currently in your Inbox, and the first time you run this version it will re-download messages that you've already read and deleted. All your accounts will be intact, though.
Thanks to everyone who's given me feedback on Hep over the past two days!