How to email Affiliates?

It seems that you can’t just email to just your affiliate group or a specific type. The only way to do it is to create a mailing list that would show up at the signup page where the user would subscribe. I want to be able to not have a news letter signup for my affiliates at signup and just email them by adding users to my newsletter blast. But you can’t search by type.

As anybody else have this issue? How do you get around this problem?

Please advise,