The subject line of your email is your entry (or quick exit) to someone’s time and attention.  After the list, it’s the most important part of the email.

A good subject line will get your email opened.  A poor one will send it straight to the trash bin (or worse, the spam folder).

Which subject line is the best?

There are quite a few factors to consider when crafting your subject line. How long should it be?  Is shorter better?  Should you personalize it by putting the recipient’s name in each email? Should you be formal? Or write more casually?

Best subject line length

Conventional wisdom says that shorter subject lines are better since they don’t get cut off in phones and tablets. However, Marketing Sherpa recently reported on a Return Path study that analyzed the length of subject lines and compared the subject length to the rate at which the emails were read.

It turned out that longer subject lines had a higher read rate (meaning more people marked it read in their email clients)

Even so, the difference wasn’t big enough to be statistically significant. The takeaway here is not so much to count letters as it is to try to tweak your subject line to get the best response from your own list.

To personalize or not?

As you can see in this more recent Marketing Sherpa article, some industries, such as consumer products, showed a marked increase in both open rates and transactions. For others, such as entertainment, the impact was negligible. Personalization used to work well overall, then it dropped off, now it seems to work well again (at least in some cases). The best approach is to try it and see whether it works for you.

Best email subject lines

As a general rule, show your readers a clear benefit in the first two words. Stay away from hard sales pitches, and include something that invites action or curiosity:

• Simple Email Change Boosts Sales 55%
• Text or HTML:  Which Gets More Clicks?
• Your Copy of Email Open Rate Study Enclosed
• A simple email marketing formula
• The Google slap is coming

Try a casual approach

With the latest political season in full swing in the U.S., candidates from both parties are frantically trying to raise money. One side is doing much better than the other.  They test and retest everything, and often find that a simple, “[candidate/celebrity] wants to meet you” or invitation asking readers to join them for an event outperforms more conventional subject lines.

Use emotions and hot button issues

Try a subject line that reacts or references recent news or events, or expresses outrage at something they’ll also find objectionable, “media says I’m to blame.”  Use a call to action to encourage your readers to do something (take advantage of a special offer, buy a new product, pass along something to a friend).

Keep it short (generally)

Top performers are usually short (30-40 characters) and this is usually seen as the ideal length for an email subject line.  However, longer subject lines can work better with a download, such as an ebook or a report.

Worst performing email subject lines

Anything that sounds too pushy, talks about the sender (rather than the recipient), or asks for an action before gaining trust

• Uh oh
• Forward this to your friends
• Big Riches, Small Investment
• ENDS TONIGHT! Training expires AT MIDNIGHT

The first one is negative and so vague that it’s discouraging. The second one asks you to spam your friends (no thanks).  The third is just plain spammy. The last one looks like it’s shouting at you.

Compare performance

Look at your own data. See which subject lines got the most opens and click-throughs to your sales page.  Also check to see which emails had the highest conversion rate (signups or sales).

If your list is large enough, try a sample of a few thousand names.  Test two subject lines against each other and see which one performs better. Then roll out the winner to everyone else.