Unfortunately, as a result, businesspeople are finding their e-mail inboxes more crowded than ever with messages that aren’t exactly spam but that don’t contain information they need immediately either. To stand out, marketers must make their e-mails relevant, said John Rizzi, CEO of e-Dialog, a Burlington, Mass.-based e-mail services and consulting firm. “Otherwise, people will revolt and vote with their opt-out button,” he warned.

One way to make e-mails more relevant is to segment the recipient list, sending messages only to people who will really care about the information. Rizzi offers the following tips:

1. Do the math. Show why you need to spend more for segmented campaigns by making assumptions and calculating how much cash you need to shell out to send more relevant e-mails, Rizzi said. Show the potential lost value of losing a customer forever if he or she opts out after receiving irrelevant e-mails from your company, he said. “Segmentation costs more, but it’s more profitable; and you can prove it with good calculations,” Rizzi said.

2. Identify the engagement level of people on your list. You should send e-mails to those people who are actively looking at your Web site and may be ready to make a purchase at the time you’re planning a segmented campaign, Rizzi said, but he cautioned that’s not enough. “Watch where they’re going, and use that information to determine the specifics of the e-mail you send them,” he said.

For example, someone actively browsing for a laptop isn’t likely to buy a printer, regardless of the discounted offer you may include in a targeted e-mail blast, Rizzi said.

3. Don’t be afraid to send out fewer e-mails. Marketers have a natural inclination to send out as many e-mails in a blast as possible, but they need to show restraint in the current environment, Rizzi said.

“You can make more money by not torturing some on your list with irrelevant e-mails,” he said. “You will have other offers for some on the list the next time around who didn’t get an e-mail offer this time.”