6 Awesome Email Marketing Powers of the P.S. is a terrific article on the Hubspot Inbound Internet Marketing blog which drives home how powerful this traditional element of a sales letter can be, whether it’s in printed or email format. It can be a bait and hook; a final plea; an emphasiser of urgency; a more personal approach; a bonus; or a testimonial. For most sales letters, it’s not a question of whether you should use a P.S., it’s a question of which type will work the best.