Despite the expense, sending your direct mail first class instead of bulk rate can be worth it, particularly for high-end promotions, says Bob Nelson, founder and president of Nelson Motivation, a management training and consulting firm in San Diego. "First class increases your audience, and it gives you control over delivery," he says. "You know exactly when recipients are going to get the mail, and you can be pretty sure they're going to open it, especially if the envelope has a first-class stamp."

Nelson is a speaker for the two-time Inc. 500 company Wyncom, a producer of high-end business seminars. He says that Wyncom runs about 175 programs a year in cities throughout the United States and sends out about 50,000 direct-mail pieces per program--all via first-class mail.

Wyncom reports that first class is successful because it generates strong seminar registration and provides a mechanism for tracking the exact number of people who received the mailing. First-class mail also makes it easier to keep mailing lists up to date because information about incorrect or changed addresses is returned to the sender.

As for return on investment, Nelson offers the following formula: At a cost of about $1 per piece (first-class postage, envelope, address label, marketing literature), you'll spend $1,000 per 1,000 names. If 1% of recipients respond (a reasonable response) and spend an average of $100, the gross will be $1,000--the amount of your direct-mail outlay. "If you have high-quality products or services and know specifically who could best benefit from them, there's no better way to go," Nelson concludes.