In baseball, if you succeed three times out of 10, you’re an All-Star. It’s the same in e-mail marketing.

On average, only about one in four e-mails sent out by a marketer is actually opened by a consumer. And that’s not just for random blasts; that includes e-mails sent to lists of customers who have signed up to receive them.

The crucial element in a marketing e-mail is the subject line. A great deal of study has been devoted to analyzing what makes a good subject line. Not surprisingly, the rules of good subject lines are like the rules of good writing: shorter is better, and active words are better than passive.

A lot of testing has also gone into the design of e-mails, with eye-tracking studies and “heat maps” showing which elements of the e-mail body readers pay most attention to. It’s pretty clear that readers pay most attention to the information near the top of the e-mail, then start skimming as their eyes move down the page. This holds true whether there are visual images in the e-mail or it’s all text. So marketers are well-advised to put their strongest material up top. If you save it for a big finish, you’re probably wasting your effort.

At Fast Horse, we’ve been handling an e-mail program for a client that has seen open rates in the mid-to-high 30 percent range, a Joe Mauer-like performance. I won’t take credit for that; I think our client has a strong mailing list and a superior product that people want to learn about. (Send me an e-mail, and I’ll tell you about it.)

But big changes are brewing in the e-mail world. The current models are based on an audience that’s sitting in front of a desktop or laptop computer. But more consumers are getting their e-mail on smartphones. This change is going to force e-mail marketers to rethink how they deliver their messages, possibly sending only a compelling subject line with a link to a website where the rest of the information will reside.

And, of course, Google is getting ready to roll out a game-changer. (Is there any area of the information world that Google can’t effortlessly dominate?) The information colossus last week gave the world its first peek at Google Wave, which is being billed as the e-mail of the future.

Google Wave, set for official release later this year, combines e-mail and instant messaging with rich text, graphics and photos. To me, it sounds less like something completely new and more like a wiki on steroids.

But with the weight of Google behind it, most of us will doubtless be catching the Wave by this time next year. And then we’ll have to develop some new measurement standards to decide who’s staying in the game and who’s going to spend the All-Star break at home.

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.

What could it be?

Ah, yes, an ElfYourself email.

Slightly miffed when I explained that this campaign was in its third year, she sniffed and said “well, check your email.”

For me, this conversation only reminded me that while we discuss email as a dying form of communication for millenials, it’s a constant for the Boomer and older generations. And they’re just getting comfortable with it to a certain extent (embedding links, adding pictures, etc.).