You Need To Know The Truth About Your Transaction
Now, I don't know about you, but usually I glance through the spam folder before deleting everything in it.
A moment before deleting, I notice an email with the subject "You Need To Know The Truth About Your Transaction"
Of course, I say to myself "Brr... probably another spam email". Ok, so delete...
"Arghh... I just wanna see what's inside!" - my curiosity was so overwhelming I had to open the email even though I KNEW it was spam.
Think about it though: what subject line could you write that's so compelling your readers can't help but open it.