Most US online merchants offer you a discount on your first shipment when you sign up for their email service.
If you are looking for a discount and your favorite merchant does not offer too many promotions or it has been a while, try signing up under a new (different) email address. Most of us have a second “burner” email for “signups” when you don’t want to share your personal email address.
Generally, you don’t have to go to such extremes. You can try to log on and leave something in your cart for a day or two and there is a good chance the merchant will email you an incentive to “complete” your purchase.
But if this doesn’t work and you can’t wait for the next big holiday sale, signing up with your burner email can give you a faster way to get a discount you are waiting for.