Didn't PostRoadMailer get opensourced and rewritten in Java as Polarbar mailer?
Polarbar is the open sourced version of J-Street Mailer, which was the Java-based email client that Innoval sold. However as I recall it wasn't a straight port (although I believe there was a bunch of shared code - if I recall correctly it was the same team of people doing the coding on both).
Regardless, the one I'd like is PostRoad, as the native OS/2 client (I still have it installed on my OS/2 partition, bugs and all!). I was never a big fan of the Java client.
At this point I don't even know if the source code still exists. I've emailed Dan Porter a few times to ask about it but have not received a reply. That suggests that I either have an incorrect email address for him (very possible) or he isn't interested (also possible). Either way is fine - it is his choice after all. Bit it is one app that I'd love to see the source made available.