The answer to most "can I do this with nmh?" questions is usually "yes!".
With the exception of IMAP, sadly. But the flip side is ... you usually
have to write that bit. And we're not so great on documentation, and the
book you mention was written quite a while ago when dealing with multiple
email addresses was uncommon. nmh has a lot of features that book doesn't
mention.
I think I have much to learn about the mh/nmh way of doing things,
considering that I am only able to understand about 75% of what the
other replies are saying. Would you recommend that I finish reading the
book? Perhaps I would be better qualified to ask substantive questions
once I have covered all the basics. I'm just hoping that the book is not
too outdated.