For instance, words such as "private," "flash," "inside," and "hot," which used to draw response when used in e-mail subject lines, no longer do, Lewis said. Others, such as "I'm about to give up on you" ("people don't want to be excluded," Lewis said) and "Junk mail? Hell no" (not the weaker "Heck no") can still work but aren't foolproof. Among the subject line phrases that still work today are "Please confirm:", "What's your excuse?", "Feedback, please.", and "What are your plans for the holiday?" But given how rapidly things change online, Lewis added, "I'll guarantee these for the next two weeks only."

Lewis also advised against using initial capitals in catalog headlines or in e-mail subject lines; tests have proved sentence-style capitalization to be more effect, probably because it's less overtly advertising. The more "click here" links in an e-mail message, the better the response. And adding a recipient's name to the subject line enhances response. What's more, if the recipient is a previous customer, rather than a prospect, generally speaking you should use the first name, to assume a relationship. "If someone came up to you in the exhibit hall and said, Hello, So-and-So, you wouldn't say, I don't know you. Instead you'd say, Hello, how are you--looking at his badge for his name, of course."