There are tons of software that let you do this on the net, I don't believe
it is so hard to do , however this would certainly require to create a new
command in nmh and the addition of a few new options in the existing commands
Sigh. I can see I'm not going to convince you. While some software exists
to perform spam detection, integrating it into nmh would be ... challenging,
especially if you want to avoid downloading the whole message.
However at the protocol level (POP3) everything already exists.
I believe the Spam filters that use POP3 simply download the whole message
then make a decision, so that's not what you want.
It is too bad I am not a programmer , so I can't help you with the task.
I am just a lowly user :)
That's the rub, now isn't it?
--Ken