I received an email like this a very long time ago, sent it back and stated that I was already an affiliate. In that note I asked when they were going to use SSL in their checkout.
Now they have SSL and I have been trying to use them more. I use to receive quite a few checks from them, and am looking forward to getting more again. Although, I do wish they would have let me know when they installed it!
As far as the email being SPAM, I like this kind of SPAM. Real contact info, real reply address, real money making opportunity.