Getting people to at least open your e-mails has become like leading the proverbial horse to water. You can send the e-mail to the horse. The horse might even be really thirsty and expecting your trough of refreshments, but that doesn’t necessarily mean they’ll drink, er open up the e-mail.

By now, most e-mail readers ignore “Read Request” notifications. Ditto marking an e-mail “High Priority.” So, what’s left?

Like leaving a detailed voice mail message, you can do the same with the subject line of your e-mail. Be as specific as possible with your subject line so the recipient knows why you’re writing. A colleague of mine has even taken to writing “ALERT” and other short descriptive phrases in caps at the beginning of the subject line to get people to read important e-mails. It may sound a bit hokey, and read that way, too, but it can work. And if the bottom line is to get them to read the e-mail, does it really matter? Not a lick.

Another reason for keeping e-mail subject lines short and sweet: spam blockers. In trying to block unwanted e-mails, some spam blockers flag questionable subject lines.

For example, try sending anybody an e-mail with a $ symbol in the subject line. That one will never see your in box. A number of spam blockers also don’t take kindly to e-mail with no subject line or short subject line greetings like “Hello.” Also, you’ll want to be careful about sending e-mails with url’s in the subject lines.

While spam blockers are meant to prevent unwanted mail, they sometimes have the same effect on the missives you do want. Sure, you can’t control what people send to you, but you can make sure your e-mails get there by paying more attention to your subject lines.

E-mails, like any other collateral, have become a struggle to get the reader’s attention—even if it’s a personal note to a friend. And the key to getting somebody to read your e-mail, much like the key to getting somebody to read your ad, Web page, press release, or direct mail letter, is the headline. When it comes to e-mails, your subject line is your headline.

Sure, this may sound like an extreme measure to take, especially for a personal note. But think about how you view e-mails. Are you more likely to read one with no subject line or one that states some sort of purpose? Will you read an e-mail with a subject line that says “Hello” before one that says something specific like “Potential new client” or “Meeting availability?”

Granted, it depends on who’s sending you these e-mails. Even e-mails from friends we rate based on the subject line, particularly during the workday. If it doesn’t have a subject line or says something simple like “hello,” we’re more likely to put it aside for a later time.

For business e-mails, it’s even more critical to treat subject lines like headlines. This doesn’t necessarily mean you have to be ultra creative. Just to the point. Remember, most people get more e-mail than they can handle. Most of us want to know what the e-mail is about without actually reading it—kind of like how we read headlines of a newspaper before committing to a particular article.

So be specific, to the point, and, brief. Try to keep the number of characters in your subject line to 72 characters or less—preferably less. Like anything else, the less work you make the reader do, the more likely they are to do what you want—in this case, read your e-mail.