THe worst thing you can do is to give up on them. You never know when someone will become active in this business, so you're only hurting yourself if you decide they are not worth your time.
It doesn't take any more effort to send them your regular team mails. Keep them on your mailing lists and keep sending them useful information. One day you may send them something that actually clicks with them and they could turn out to be a star affiliate. Never give up!
