Editor’s note: This is John Reinan’s weekly marketing column for MinnPost.com. To see the original, go to http://tinyurl.com/bdbcxt.

In a struggling economy, marketers turn to e-mail.

According to MarketingSherpa, a leading supplier of marketing research, 60 percent of the companies it surveyed were planning to boost e-mail marketing in 2009 to their existing lists.

Another 30 percent planned to increase e-mails to rented lists– something of a dangerous proposition because of the unpredictable quality of rented and purchased e-mail lists. But that’s just another data point showing that marketers buy into the general effectiveness of e-mail.

E-mail marketing is an interesting cat-and-mouse game. Consumers love to complain about spam. Yet the percentage of delivered mail that’s opened and acted upon remains consistently high. In other words, if you get by the spam filters, customers are generally interested in looking at your message.

In addition, consumers are very willing to begin and maintain e-mail relationships with companies they value and trust. The numbers are quite high: More than 60 percent of Americans have an e-mail relationship with a bank, credit card company or other financial service provider.

Nearly 60 percent have e-mail relationships with online retailers such as Amazon or Zappos. Nearly 45 percent of Americans have e-mail relationships with traditional brick and mortar stores, while 40 percent have relationships with restaurants; travel services such as Orbitz; and online services such as Netflix or iTunes.

That’s a lot of e-mail– and it’s e-mail that the consumer has invited and welcomed from you. The average consumer maintains anywhere from two to six e-mail relationships within each of these categories.

The successful e-mail shares many characteristics with other successful media. Shorter is better; Americans don’t have long attention spans. Break up long blocks of text. Photos, graphics, bullet points and bold-faced text, properly placed, help readership.

One of the most important things you can do is promise not to share your customers’ e-mail addresses. About 75 percent of consumers said they were more likely to opt into an e-mail program if they knew their personal information wouldn’t be shared.

Offering e-mail subscribers special deals on pricing and a first look at new products and services also are good ways to increase participation.

The more I learn about e-mail marketing, the more fascinating I find it. It’s a very interesting combination of the creative and the objective. You can test everything and see how it affects response: What if we made this banner red instead of blue? If we go to double opt-in, will we get higher quality leads? How much registration information should we ask for? The barriers to entry are much less than in print, so experimentation is less costly.

In times like these, any business would welcome an inexpensive, effective way of generating qualified leads. E-mail is one they should be considering.