Thompson's link to the Libraries and Archives with Jewish Music Collections (great find!) has an FAQ that might be helpful (and is international):

Q: Do you answer questions?

Answer:

YES! I do try to answer all my email questions, in some way. I’ve had questions from all over the world from as far away as Manila and Sydney, and as close to home as, well, as Brandeis University students!

I don’t do your homework. I can help you find a book, but I don’t read it for you.

I don’t fax or copy pages from articles or books. I don’t provide document delivery. I will help you with a citation though, and try to let you know where to find information.

The Contact Us link goes to a form, so I think that is your initial "email" contact method. Once it sorts real people from spam, you probably get a direct address.