Really cool one. Another I found works well is Do not open this email. Hell i even opened the damn thing I knew it was some junk mail hahasend them an email with the headline as "Are you an idiot?"
Read it in a thread a while back - really high response rate.
Add something in the email with affiliate links or something.
Try and get information from them! Ask them to go to a site which will
capture their data. Then use that data!