Steve Rennekamp, owner of Energy Swing Windows, in Murrysville, Pa., mails to previous customers every six to eight weeks. He doesn't worry about becoming a nuisance by over-communicating with them because he trusts the relationship he has built with his customers in the first place.

“We make a tremendous effort to build rapport with our customers,” Rennekamp says. “So when we [mail to] them, it's not like they feel we're intruding, in most cases.”

Scot Hayes, owner of New York Sash, in Whitesboro, N.Y., agrees. “I believe that there is a fine line in regards to contacting previous customers too frequently,” he says. “But if you've done the right thing and have done a good job for your client, they welcome some of the contact.”

HOW MUCH IS TOO MUCH? Hayes is conservative with the number of his contacts. “We've had tremendous success with two major sales a year” he says. Postcards followed up with a phone call “go to all past customers, twice a year, every year” in July and December.

Hayes also periodically contacts customers who have expressed a future interest in a specific product, such as sunrooms, when that product is on sale.

Hayes says he feels that with “a mailer and a phone call two times a year, you're definitely safe” from burning out previous customers on your marketing.

NEWS LETTERS DO IT Newsletters as vehicles for information, which also contain product or service offers for customers, are a way to legitimize repeated contact.

Maggio Roofing, in Takoma Park, Md., recently began testing twice-per-month mailings — a mix of specific offer letters and a newsletter — to past customers, says president Scott Siegal. Formerly, the company mailed a newsletter four times per year, but informal research led Siegal to believe that this was too infrequent. “So we started sending the newsletter once a month, and as soon as we did that, I began getting calls,” he says.

Siegel describes the newsletter as “purely informational,” while the direct-mail offer letters are designed to “offer [prospects] something.” The newsletter and the offerings vary with each mailing.

Siegel says he has no way of knowing if the program will spark as much interest a year from now. “All I know is that lead costs have gone through the roof,” he says. “If we don't leverage our past customers, I think we are being foolish.”

And it doesn't take much added business to more than cover the cost of the mailings, he adds.