They say life isn't fair. Maybe so. But you know what is most definitely not fair? That you can work your tush off getting a visitor to your site, can have them spend time shopping around, adding to their cart, and then...they could get distracted (their Bernedoodle barks, they get a ping from their mother-in-law, their popcorn is ready, etc), and then be gone forever. Leaving you, the sweet eager shopkeeper without a way to email that visitor.