Because the subject lines on your messages aren’t motivating customers to click the darn messages to open them, that’s why!  So let’s hold a little Email Subject Line Boot Camp right here and now.

Email Inbox ImageFirst, the Testing Disclaimer: No subject line idea is guaranteed to work for your business unless you test it. Testing one subject line against another is easy. Read this article to learn more about email testing, before you go any further.

Back already? OK, let’s start with a special offer just for you: The Secret Ingredients of the Successful Subject Line.

The most clicked-on subject lines are

1) very relevant to the reader and 

2) very timely

(Nobody said a secret couldn’t also be obvious.)

Look at these successful subject lines (with company names changed) from a survey last year by email vendor MailChimp:

Preliminary Floor Plans for Southern Village Neighborhood Circle Members

  • This specific announcement of a new condo development got a 93% open rate

Your April Website Stats

  • Timely + personal = 92% open rate

Idlewild Camp – Important Travel Information

  • Need-to-know information. 90% open rate.

Notice something else about these subject lines?  They’re boring – but very direct and informative about exactly what you’ll get if you open the message.  

And that comes up consistently in email metrics. “The best subject lines tell what’s inside, the worst ones sell what’s inside,” MailChimp concluded.

But wait a minute, you say. WAIT A MINUTE!  What about ALL CAPS, “sale”, “limited time offer”, “free” and all the other hot button terms and punctuation competing for your attention in your inbox?  Increasingly, email users are passing up those hard-sell subject lines, open-rate studies find.

From the same MailChimp survey:

Tempting August NUSA Special!

  • 0.9% open rate, despite (or because of) “special” and the exclamation mark.

SALE ends soon – up to 50% off all bras at Kara!

  • 1.9% open rate. Per cent off is a buzz kill, apparently.

Major Exception to the Rule: If your email subscribers have signed up to be informed about sales, then by all means, fire away with the ” % off”, etc.

For more words to avoid because they sound like spam or worse, they could prompt an email service to send your message to the spam folders, ­see this list of the best and worst subject line keywords.

So boring, straightforward, zzzzzzz all the way, right?

Not at all. There’s plenty of room for the intriguing, the provocative, the surprising and the mysterious, if you can carry it off (and test first!).  Look at these subject lines and the amount of money they earned:

Some scary numbers

  • $1.9 million

Would love to meet you

  • $755,000


  • $711,000

The last one probably gave it away. These were fund-raising email messages sent by the Barack Obama campaign in 2012, Business Week reports. Well, you might say, with a  “from” line like “Barack Obama” you could get an open with a subject line like “Hey” or “Wow” (actually, the campaign sent those subjects, too) and yes, they are a reminder that the reader considers the “from” line and the subject line as a whole so the two need to work credibly together.


Hey.  Here’s a short guide to subject line length, from a study by MailerMailer

 4 to 15 character subject lines got the highest open rate: 15%

Over 50 characters the lowest open rate: 10.4%

So keep it under 50 characters. But also be aware that some email clients cut off subject lines at 27.


To end on a personal note…

Your email program most likely allows personalization of the subject line, for instance by adding the message recipient’s name. But should you?  The MailChimp subject line study found that the recipient’s name didn’t improve email open rates but adding the recipient’s city name did. And try adding your company name or brand name to the subject line to reinforce credibility.

For more ideas on subject lines, check out this reading list: 

Subject Line Best Practices Infographic (Litmus)

10 of the Best Email Subject Lines  You’ve Ever Read (HubSpot) 

6 Simple Steps to Response-Driving Subject Lines (Return Path)

Don’t Roll Out the Loser: How to Analyze Subject Lines (Return Path)