3. The scarce subject line

Actually as old as history goes back. While we may not like to admit, the fear of loosing out is a baked reflex in human.

A few examples:

Only today: Free shipping with your order

Only 3 places available in our seminar

Our sales will end tonight at 18:00

Market merchants use this technique when you pass their market stall on Saturday afternoon "The last 3 bouquets of yellow roses!"

And you can also make use of it in your email newsletter.