Ok Spammer. The first thing you need to do is make sure that you are compliant with the spam law. Opt in or not you have to.
Make sure also that the customer knows where the mail is comming from. Using a single subject line will always help. Also tell the customer when he opts in, to watch for mail with " AAAAAAAAAA" subject line. If they find it in the trash bin, to make sure to put it in the good mail folder.
Now Die spammer!
