If genuine, all that stuff is associated with a program called PGP - Pretty Good Privacy.
PGP, first developed in the '90's by Phillip Zimmerman, an American, is an excellent encryption and digital signature program. The program is so good that the FBI wanted the code so that crims wouldn't have an advantage over them. Zimmerman "declined" and all sorts of harassment followed, including imprisonment or the threat of it. Eventually 2 versions were released, one for the USA for which the FBI holds a "master key" and one international for which they don't. (That may have changed since 9-11). So much for the potted history
What you're seeing, if it's genuine, is the digital signature of the sender, and yes, the two things are related.
If the email is spam it's possible the spammer has cut and pasted the digital signature stuff from another email, or has actually used PGP to make his rubbish look more genuine.
You can check if a PGP digital signature is valid only if you have PGP installed yourself (I think). There are versions for various operating systems, hence the reference to Free BSD.
You can find out more about PGP
here. It's quite interesting.
AA