Marketers have consistently shown that transactional e-mail leads to significantly higher conversion rates, meaning more people convert from shoppers to buyers when they receive a transactional e-mail versus a regular e-mail. It's understandable considering that within the body of the message of a transactional e-mail, the recipient can view merchandise, select items, and submit an order. Just like on an e-commerce site, when the order form is completed, the customer clicks the "submit" button (and can then resume reading their other e-mail messages).
Here's a great example: Zagat's, a well-known distributor of restaurant guides, tried transactional e-mail sales for the 2000 holiday season, allowing customers to buy restaurant guides directly from the body of the e-mail message, rather than just including a link to their Web site. The campaign attained conversion rates five times as high as those of regular e-mail marketing. They believed this high conversion was due in large part to impulse purchases because the transaction could be completed before the customer grew weary of the procedures involved.
NetLingo Classification: Online Marketing