“Too many of these can lead to list exhaustion so use sparingly and, of course, only when there is truly a deadline, limited quantity or limited availability.”
Sometimes, all you have to convey in an email subject line is a sense of urgency or scarcity. These types of subject lines tell readers that they must act now to get something, buy something, or have their lives made better in some way. They’re the most powerful subject lines in your marketing arsenal.