• Dos and Don’ts of Marketing Email Subject Lines

Email Marketing Subject Line Dos and Don'ts

Compared to social media platforms, live chat bots, and project management applications,  the term “email” seems outdated. However, email marketing still works. That is, if you can get your readers to open your emails. Which is, if your emails make it to their inbox in the first place.  Writing effective email subject lines is a craft, and can greatly impact your email marketing metrics. Read on for email subject line dos and don’ts that will maximize the results of your email marketing campaigns.

Related [free] eBook: Email Marketing 101

Email Marketing Subject Line Dos and Dont's

Email Subject Line Dos

1. Keep it short and sweet.

(50 characters or less, 20-30 is ideal) to prevent it from getting cut off or from annoying readers. Tile creates a short and simple one here:

Email Subject Line Dos 001 simple number

2. Include content type in your email subject line.

Especially if you have one list and diversify your emails (some are promotional, some are updates, some focus on events, and others on content downloads). Make sure readers know exactly what they’re getting out of the email.

3. Make subject lines clear. Let the reader know exactly what to expect in the most efficient way.

The first email subject line example from Elevate doesn’t really help the reader to understand what the email is about. The second subject line is a vast improvement of this subject line must-do.

Email Subject Line Dos be clear

4. Grab attention with words that resonate with readers.

Stitch Fix knows how to connect with its audience. For people who want to choose from a selection of quality clothing,  “100+ premium brands” is great word choice.

email subject line dos

5. Learn about the laws of spamming, to ensure your emails make it to inboxes in the first place.

6. Use language that your readers recognize.

Drift is clearly sending this email to its users, so it can use terms like “LeadBots” to grab their attention.

email subject line dos

7. Include a call to action phrase (when applicable). Register now! Download your free E-book!

8. Use personal data if you have an accurate system.

email subject line dos be personal

9. Offer the value or benefits right away.

Although their subject line is a bit too long and gets cut off, TouchCare does a great job with conveying value:

email subject line dos

10. Quantify when possible.

This email subject line gives readers a finite time frame, an ideal way to increase engagement with your emails.

email subject line dos

11. Incorporate your brand voice or put a creative spin on your subject lines (when it makes sense).

12. Include numbers.

This helps readers to quickly identify the promotion being offered to them.

email subject line dos

13. Convey urgency, especially with promotional emails.

Encourage your readers to open the email before the offer inside of it expires. This email from Boston Sports Clubs does a great job with their email subject line:

This Idealist email conveys less urgency. This makes sense because the date of the fair is two weeks from the email, but if they wanted to create more urgency, they might have said “Don’t miss the Boston Idealist Grad Fair coming up!” or “The Boston Idealist Grad Fair is in just two weeks!”

14. Refer to trending topics to catch your audience’s interest.

15. Engage curiosity

The Elevate example above slightly taps into the curiosity factor but the quotes and lack of clarity detract from its effectiveness. Stitch Fix below uses their language (“fix”) and triggers a sense of curiosity that feels safe for the reader.

Email Subject Line Dos be clear

email subject line dos

Email Subject Line Don’ts

Here’s what NOT to include in your email marketing subject lines to prevent your marketing emails from getting ignored, deleted, or spammed:

1. Attempt to deliver multiple messages in one subject line.

Only deliver one clear message in each subject line and email. If you try and communicate too many ideas at a time, you run the risk of all your information becoming white noise to the reader.

2. Be inconsistent with caps.

This is an actual spam email, but you can see how unprofessional and spammy a subject line looks when the capitalization is inconsistent.


3. Grab attention with too many exclamation points or spammy words.

This also is a spam email, but once again you can see how multiple exclamation points appear. The single exclamation point in the Boston Sports Club “Hurry!” email subject line is enough to convey excitement.

email subject line donts

4. Use personal data if you aren’t sure if you have all information on every lead.

The last thing you want your email recipients seeing in the subject line is your business greeting them by their email address or with a blank space.

5. Try to “bait” readers with inaccurate information or false promises.

Your subject line needs to deliver on its promise about the email that follows.

6. Try to build curiosity with not enough info.

This is an email from an organ donation nonprofit, but the mysterious subject line doesn’t provide enough intrigue or security for the reader to click.

email subject line donts

7. Use the same email subject line every month for your newsletters.

You will lose the interest of your readers. If the same subject line applies each month, then you probably need to diversify your email newsletter content a bit more.

email subject line donts


Your subject line serves as a portal between your company’s message and the recipient. Though they are small pieces of content, they play a major role in building trust with your audience and generating leads through email. Follow these email subject line dos and don’ts to ensure you get the most out of your email marketing strategy.

Kristen McCormick
Kristen McCormick
Kristen is the Content Marketing Manager for ThriveHive, where she geeks out daily over SEO, organic traffic, and A/B testing. When she's not equipping business owners and marketers to get their name out there through effective content, she's out pedaling the streets of Boston on her beloved bike.

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