Windows/Mac: Postbox is an email client that helps you re-discover all the photos, attachments, and links buried in your email, as well as organize newer mail. Think of it as Thunderbird with a file-managing fixation.
In fact, Postbox is based on at least a good chunk of Thunderbird's code, and most of its company's founders and lead developers worked on Thunderbird or other email apps at Netscape or Mozilla. If you're already a user of the open-source bird, Postbox should be strikingly familiar, but Postbox can also be picked up pretty easily by any new user.
