Content Marketing, Email

The Art of Subject Line Copywriting

One of the first things your consumers see when they receive an email from you is the subject line. Often, the subject line serves as the determining factor in your email being opened, deleted, or marked as spam. There are a lot of different strategies companies employ in their subject line copywriting; the results range from excellent to terrible. What makes a compelling subject line? Let’s discuss the art of the subject line copywriting.

The Bad

Let’s start with the bad. Have you ever gotten an email with a subject line like these:

  • HURRY THIS WON’T LAST FOREVER (The scream at you in all-caps sales tactic)
  • FREE!!! Click now to secure your offer!!! (The over the top punctu-izer)
  • Re: Your free offer is still pending (The fake reply)
  • You won’t believe this new study on how you can lose… (The click-bait cliff-hanger)
  • Hi (The mysterious single word subject line)

Chances are pretty high that you’ve received all of these like a trillion times. These types of subject┬álines are designed to trick consumers into opening emails; the user gets no real understanding of what the sender is offering. Emails with these subject lines are also often associated with spam, scams, and viruses.

You aren’t sending spam though, so why not capitalize on what’s working even if spammers are using it? These can increase open rates, right? Wrong. While it’s true that these tactics can get the unsuspecting consumer to open an email, there are several reasons to avoid this today.

First, consumers are becoming smarter.

I know you may have fallen victim to one of these scammy subject lines in the past, I know I have. But do you still fall for them at the same rate today? I would venture to guess no. Consumers, in general, are learning and adapting the way they interact with email. The fear of missing out on these clickbait subject lines is becoming less of a dilemma for the modern consumer; many delete anything that doesn’t look “legit” to them on sight.

Second, email clients are becoming smarter.

You know what stops your email from being opened before the user even has a chance to see it? The user’s email provider. Email clients now deliver a lower percentage of emails sent to their users’ email inboxes than ever before. Email providers flag emails with poor subject lines (like the examples above) and label them as spam based on several criteria that are always evolving. These criteria include the word or phrase choice, overcapitalization, over punctuation, IP reputation of the sender, previous complaints, and more.

Third, it can ruin your email reputation.

I’m at a point where I mark anything with a questionable subject line as spam. I never open these emails to unsubscribe because I worry about the safety of clicking on the links in the email. By using these clickbait subject lines, you are increasing the chance that consumer will mark your messages as spam. Being labeled as spam can be a death sentence for your email marketing. When your emails get marked as spam, it counts as a strike against you. Once you get enough strikes, your emails start going to spam folders. From there, email providers can choose to stop delivering your emails altogether. Once you are blacklisted there is not much you can do, so let’s talk about what you should be doing.


The first thing to consider in writing subject lines is the length. If you do a google search, you will find a lot of great information and statistics about how long subject lines should be. For example, MarketingProfs reports that an analysis of more than 7 billion emails sent in the second quarter of 2017 show that emails with a subject line of 1 to 20 characters have the highest open and unique click rate while subject lines with 61+ characters come in second. ReturnPath, however, claims that the sweet spot is 65 characters. Data shows that the most common length is 41-50 characters.

So how long should your subject line be? Well, that depends. If your emails are being seen primarily on desktops or laptops, then you can get away with a more extended subject line. Similar to ReturnPath, we’ve seen great open and click rates on emails with a subject line of about 65 characters when opened on a computer. However, if your consumers are more prone to open emails on their mobile device, longer subject lines are often cut short which can distort your message and hurt open rates. If you are seeing more of your consumers using mobile for email, keep your message between 35 and 41 characters to ensure your full message is displayed.


You know what to avoid. You know your target length. Now, what do you write? Your subject line should tell your consumers precisely what they should expect in the email. If your email has a free resource for download, then tell them. If you have a sale, tell them. Email subject lines perform better when they are clear and transparent. As you communicate the content of the email through the subject line, however, word choice is imperative.

As we discussed before, email clients flag emails based on the words they detect and have linked to spam. Using words like “free,” “50% off”, “Click here,” and “supplies are limited” often get flagged as spam. This is where writing gets tricky. When you are having a 20% off sale, your subject line needs to communicate that without using words that are associated with spam. Simply saying “20% off sale” is clear and transparent, but will likely end up in the spam folder for all Gmail and Outlook accounts. There are resources available to aid you in selecting words that are more likely to avoid spam detectors.

For more information on email marketing or to get an extensive list of words to avoid in email subject lines, email me at

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