Email is a core part of almost every marketing strategy. Whether it’s for ongoing nurture of a subscriber base or one-off outreach to high-value prospects, email offers a huge ROI if you can get it right.

And the first thing you need to get right is that your potential clients and customers have to actually open and read your emails. It doesn’t matter how great your email content is, if they don’t get opened and read they’ll have no impact on your bottom line.

Now no doubt you’ll have seen all sorts of tricks recommended in the past to get people to open your emails: subject lines like “Hey!”, “Bad News” or “Re: your email.”

These subject lines are designed to get people to wonder what on earth they’re about, and to open them to find out. And they work.

Unfortunately, they tend to work once only.

If your email doesn’t really deliver on the promise of the subject line, then you lose the trust of your recipients. So if it’s not really bad news but instead a thinly veiled sales pitch, or if your email isn’t really “re” anything they’ve sent you before then the next time your potential clients see something similar from you, they’ll think twice before opening it.

So what works better and more reliably to get people to open your emails? The “Cocktail Party Effect”.

In psychology the cocktail party effect refers to the strange ability of human beings to home in and be able to listen to a single conversation in a crowded room and to filter out all the other discussions and general hubbub.

If we hear our name mentioned across the room, we can instantly tune in to that conversation no matter how many others are going on around us. If there’s a bit of juicy gossip being shared we manage to hear all that and ignore the person speaking directly into our ear.

The cocktail party effect allows us to instantly pick up on things that are interesting to us. And it’s the same with email.

If the subject line of an email is related to something we care about, it sticks out like a sore thumb in our inbox. Send someone an email where the subject line calls out their biggest problems, issues, hopes, fears, aspirations or goals and they’ll notice it. Their brain won’t let them miss it.

And want to get an even higher open rate than just mentioning something they care about?

Try the “Interest = Benefits x Curiosity” formula.

The benefits in the equation are those same things they care about. But by adding in an element of curiosity you can generate even more interest in opening your email.

Did you notice the headline of this article? I used the same principle there.

The benefit was “…To Get More People To Read Your Emails”. Something you’d no doubt like if you’ve read this far.

But you’ve probably also read lots of other articles on getting people to open and read your emails. What makes this one different and worthy of your attention?

That’s where curiosity comes in, and in this case, the phrase “Harness the ‘Cocktail Party Effect’…”

Unless you were already completely aware of the interestingly-named “cocktail party effect”, that title probably aroused your curiosity to find out what it was. End result: even more people opening and reading the article.

So try the same with your email subject lines. The core is the benefit: talk about the hopes, fears, aspirations, goals, problems, issues and challenges of your ideal clients and you’re on safe ground. But spice them up too with a bit of curiosity to get an even better open rate.

Ian Brodie is a consultant, blogger, and author of the Amazon bestseller “Email Persuasion: Captivate and Engage Your Audience, Build Authority and Generate More Sales with Email Marketing”. You can get a free copy of his “21 Word Email That Can Get You More Clients” on his site.