People receive hundreds of e-mails a day, if not more, which means marketers face steep competition when launching an e-mail promotion, sending out a newsletter, or revealing a new product or service to customers. If the e-mail is being sent to a group of people, or it's being sent to an unknown recipient, what matters most is a compelling subject line to insure that the e-mail gets opened—and hopefully read.

While marketers jockey for position and fight for just a few seconds of our attention, it's also incredibly easy to just tune them out. "A long time ago, you sort of had to endure the cheesy television commercials," says Hamilton Wallace, the owner of Small Business Marketing Consultant in Scottsdale, Arizona, who has 30 years of marketing experience. "Now, it's just a click—and boom you're gone. It's just a lot easier to unsubscribe."

So whether you're sending out a business proposal, a newsletter, or reaching out to a potential client, you need to have a subject line that 'sells' the rest of your message. Along with your name, the subject line is the first piece of text that will be read by a potential customer, and to get it just right, it takes a bit of artistry—not artifice.

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Writing a Compelling Subject Line: Why It Matters

The subject line is the first point of contact with a customer or potential client, like the opening line of a sales pitch. And just as advertising copy is so critical to the success and failure of a campaign, a subject line invites the reader to care. With so much of our time on the computer occupied by spam and banner ads, it's easy to get distracted. That's why a compelling subject like is essential; it must cut through the noise and capture the reader's attention.

"Nothing else happens until someone reads your message," says Mitch Tarr, owner of Zin Marketing in Napa California, a small business e-mail marketing firm. "It all starts at the beginning. If you don't get people in to read your message and read the content, nothing happens." If you want people to do something like attend an event or purchase a product, Tarr says, the subject line gives them the reason to open the e-mail and buys you a few more seconds of their time.

And it's these few seconds, says Wallace, that can mean success for the campaign, or failure.

"These 10 seconds are critically important because if you can't get their attention, you could be giving away $100 bills," he says. But if the subject line is written poorly, few recipients will take the time to open the e-mail. 

Writing a Compelling Subject Line: Understand Your Customer

All good marketing starts with an understanding of your target audience, says Dave A. Young, the principal of Young Copy, a company that provides writing and marketing services, based in Cincinnati, Ohio. To write a compelling subject line, you need to know the types of products and services that would appeal to your demographic, as well as the type of tone they're expecting from you.

"What I've learned is that the more familiar you are with them and the more you're in front of them, the more likely they'll open the e-mail," Young says. The more personal you make it, the better, he says, "just like you would do on the phone." Young urges marketers to set "the right tone and use the right words—and not use any kind of generic language that [the customer] is not used to."

Obviously, there are some e-mails a reader will always open—a daily newsletter, an offering from their favorite company, etc. But in order to get a customer 'hooked' on a product, it's important to provide a consistent approach to sending e-mails, whether it's humorous, informative, or a direct call to action. A consistent subject line, whether in tone, style, or structure, is essential to getting people to open your e-mail.

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Writing a Compelling Subject Line: Inform the Reader—Don't Trick Them

If a subject line reads "THIS IS NOT SPAM," it probably is.

"You have to treat the subject line like a newspaper headline in that it needs to inform and it can't trick," says Wallace. Just because your customer may recognize your e-mail address, it doesn't necessarily mean they're going to want to open the e-mail, especially if you send them e-mails often.

Wallace sees the subject line on three levels:

1.    It has to be seen and understood—keep it between four to five words, or under 45 characters.
2.    It has to inform. Just like a newspaper headline, a reader has to go in to the body of the e-mail knowing what they're about to learn. 
3.    It has to be persuasive without 'crossing the line.'

Crossing the line is one of the worst things you can do, Wallace explains. "It's a double-edged sword," he says. You want the subject line to be provocative, but you don't want to give misinformation. For example, "'Win a free trip to Hawaii' in a subject line is fine," he says, "but if in the details you have to do this and do that, what you've done is left a lot of people feeling tricked, and I think you've closed the door on people." Once the door is closed, he says, people may never read your e-mail again, or they may mark you as spam. "Don't be clever," he warns. "As marketers, we get our kick on this, but the subject line is not a place to be clever. I think marketers are foolish to do that."

Another tactic that's often misinterpreted is asking a question in a subject line, like "Want to save money?" Such approaches are often labeled as spam, and useless for a marketer. "You're screaming, I am going to sell you now," says Wallace. "We don't want that. I think the Internet and e-mail is moving us in the direction of not wanting to be sold to."

Some e-mail providers are also very strict about what types of e-mails get labeled as spam, says Dave A. Young. In addition to blast e-mails, you need to be careful with certain words like 'free 'or 'sells.' "Don't use words that will get caught," he says.

Writing a Compelling Subject Line: Will Your Reader Open the E-mail

Many marketers choose to measure the success of an e-mail marketing campaign by the open rate—or the percentage of people who choose to look at the e-mail, says Dave A. Young. By looking at this statistic, you'll get a sense if your subject line is working, or if it needs work.

One study by MailChimp took a look at 273 million e-mails that were sent out. Depending on the industry, 20 to 40 percent of the e-mails were opened—the rest were not. A higher open rate will lead to more conversions, which is the idea of sending the e-mail in the first place. And to have a compelling subject line, you need to be on good terms with the potential customer.

"One thing I really believe in is that the subject line by itself is only half of the equation," says Tarr. "The other half is who it comes from."