A/B test your subject lines – intuition doesn’t always cut it!

Like a good argument?

Simply ask email experts to describe the “right” subject line approach. Then step back and enjoy the fun discussions on length, branding, personalization, capitalization, symbols, punctuation and, of course, words like “free”.

Given the ongoing arguments, should you just rely on your intuition to write a winning subject line?

Unfortunately, anyone familiar with sites like “WhichTestWon?” knows that’s not a reliable approach, either.

All of which is very annoying, because the subject line is one of the key signals used by recipients to decide whether to take a closer look at an email.

So how do you pick the best subject line?

The answer is to let recipients decide for you, through A/B testing.

You create two emails, identical but for their subject lines. One part of your list gets subject line A, another part gets subject line B. The email that pulls the best results is the one you then use for the rest of the list.

Does it work?

You bet! Marketers regularly report double or triple digit increases in response as a result of A/B subject line testing. It’s one reason a MarketingSherpa survey found subject lines were the most popular email element tested by marketers.

Here are four tips to make the most of your A/B tests:

  1. Make sure enough recipients get the test emails to make the results meaningful. Talk to your friendly expert or ESP for advice on test group sizes.
  2. Judge the subject lines using the really important metrics like sales. Don’t just look at open rates.
  3. Make the difference between subject lines unambiguous so you can apply what you learn to future subject lines.
  4. Repeat tests further down the road: recipient preferences can change…

P.S. A/B tests are not just for subject lines, either. The same principle works well for testing button colors, calls to action, and many other simple email elements!

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