Looks like the Albert Yale’s site is down, but I found GM41 - not 51 - at http://www.cspltd.ndirect.co.uk/internet/clients.htm , about 80% of the way down the page.

I agree that this software is not normally necessary. Perhaps its potential for abuse is what is making it scarce. I got it at the same time as the author’s Bounce Spam Mail, and just played with it a bit. I never use it but would rather not delete it. Just wondering why it flags the detector.