The truth about subject lines

Whenever I do a podcast interview, I can pretty much guarantee that the host will ask me about how to write subject lines.

People get really tangled in knots about this—and I can understand why.

In general copywriting there's a lot of emphasis on the importance of headlines.

You hear stories about how just changing a headline can result in a 5X increase in sales from the same copy.

And since a subject line is essentially a headline for an email, it seems logical that subject lines are a high stakes game.

That's not quite true, and here's why:

One of the major reasons why a good headline can greatly increase response is that it flags down the ideal customer for your offer.

When you're placing an ad in a printed magazine, or sending out a snail mail letter, or running ads on Facebook, this “flag ‘em down” effect can be huge.

However, once you've identified a group of people who are interested in what you sell, the headline choice has a much smaller effect.

Case in point:

Lately I've been doing a lot of work with outbound email (aka “cold email”) for B2B service firms.

This process involves carefully building a hyper-targeted list of 5,000 or so contacts and sending them short, personalized emails to gauge their interest in the services my clients offer.

Now you'd think that the subject lines would be really important here, since these contacts have never heard of my clients before.

Not quite…

Right now I have one test running with two completely different subject lines—the A variant is getting a 68% open rate, and the B variant is getting a 67% open rate.

With optin email lists, what I've seen is that open rates tend to vary plus or minus about 10%.

So if your open rate averages 20%, an attention-getting subject line might bump it to 22%, and a really poor subject line might depress it to 18%.

The takeaway here:

Because a good email list is by definition already “sorted,” the subject line doesn't swing the results like you might expect.

That's not to say that the subject line is irrelevant—it still deserves some thought.

Tomorrow I'll share some guidelines that I've found helpful in crafting solid subject lines.