Best Practices for Email Subject Lines

By Yuri Burchenya read
05 Jun, 2015

What is the most important part of sending any email?

I’ve been doing this exercise of noticing which parts of the email I am paying attention to.

So far the pattern is pretty clear. Here are the top five things that I pay attention to when reading an email (even if I only skim over):

  1. How people greet me
  2. First sentence
  3. The list (if any)
  4. Photo of a person
  5. P.S. section

You can debate whether this list should be used as a universal guideline when designing and writing your next sales letter, but one thing is clear. I wouldn’t even have the chance to notice all these things, if the subject line did not motivate me to open the email.

So how do you write a subject line that gets reader’s attention in the overcrowded email inbox, and makes him take action based on those couple of words?

Plan Ahead: Subject First

Make sure you plan your email newsletter ahead, and that means figuring out your subject line way in advance. Always remember that it’s the only part of the email that most of your recipients will see. Pay extra attention to crafting a descriptive subject line, as it will also help you focus the narrative for the rest of the email.

Hold Their Hands: From Attention To Action

Think about what is that one thing you want the recipient to do after reading your email. Remember about the AIDA (attention, interest, desire, action) framework. Then begin drawing them towards this action in the subject line, by using verbs and power words.

When you’re sending a promotional email that intends to sell one of your products, always be upfront about the actual value that your offering and work on including a sense of urgency. If you’re selling a recipes collection book, a good subject line to send to fellow foodies might be “The Last Cookbook | 50% Off Today Only | Email-Only Offer”

Avoid These Words

When writing an email subject line, one extra thing you should keep in mind is the spam filters. Those are powerful algorithms that usually work for your own good and make sure you don’t get any unsolicited spam email in your inbox.

However once you start sending promotional emails to your own subscribers, you can find yourself in a situation when your emails will be captured by the recipients spam filters, because you decided that “FREE OFFER! CHEAP RECIPE BOOK | BUY NOW!!!” is actually not a bad idea for an email subject. Wrong.

Luckily, there are lists of these spam trigger words that are available for you to take a look next time you compose a subject line.

Though spam filters are scary, they’re shouldn’t be the sole focus of your attention. After all, it’s the recipient of your email who will decide whether he is intrigued by your subject line enough to open it, or not. According to research from Mailchimp, there are three innocent words that tend to drop the open rates for the newsletter campaigns sent through their system.

We identified innocuous words that won’t trigger a spam filter, but will negatively affect your open rates. They are: Help, Percent off, and Reminder.

Stay Concise And Precise

There’s no silver bullet when it comes to the length of an email subject line. Some merchants can get away with subject lines like “!”. Yes, that’s right, just an exclamation mark. The same study from Mailchimp showed that:

“Our analysis confirmed the email marketing rule of thumb: you should keep your subject line to 50 characters or fewer. One exception stood out. For campaigns whose subscribers were highly targeted, the readers seemed to appreciate the additional information in the subject line.”

Just keep in mind that your customers with iPhone will only see the first 35 characters (around 6 words). And that it’s always a good idea to send yourself a test email and check how it looks both on your smartphone and PC.

Over to You

No matter how much time you spend on writing that perfect subject line, there’ll always be some people who just won’t open your email. And that’s ok. If you’re trying to appeal to everybody, what you’re really doing is appealing to nobody. So focus on that segment of your audience that’s most likely to buy and do your best to give your product a chance to be seen.

Did you find any of these tips useful? Do you have a strategy for writing subjects that always get a high open rate? Let me know in the comments section below.

Yuri is a Content Crafter at Sellfy. He's focused on inbound marketing, copywriting, CRO and growth.