13 Best Practices for Email Subject Lines

Best practices for email subject lines are relatively easy to follow and they will increase your email campaign open rates. Writing compelling email subject lines will still require you to put on your thinking cap but, together with the 13 best practices in this article, you are sure to get the attention of your target audience!

In our article on the Top 10 Construction Marketing Ideas, email marketing is in the top 5 and rightfully so because of its effectiveness on generating leads and new revenue streams.

According to CoSchedule, the average return on investment per email is $38 for every $1 spent. That’s good ROI! But at the same time, stats show that 35% of customers open emails based solely on the subject line…nail-biting stats, right?  

So, how can you not stop thinking about the email subject line that will get the recipient to open your message? And after you finally commit to one (or two, with A/B testing) and send, you start sweating it. You try to refrain from checking open rates every five minutes. You hold your breath. “Will I regret it?”!

If you follow established best practices for email subject lines in this article, it will take some of that heat off you. The best practices are relatively easy to apply and they will increase your email campaign open rates. Coming up with compelling email subject lines will still require you to put on your thinking cap but, together with the 13 best practices in this article, you are sure to get the attention of your target audience! Our article will summarize each one and provide several examples to demonstrate both best practices and bad practices.

1. Keep them short, snappy, and simple.

Most email service providers will prompt you to keep the email subject line of your message short and to the point as you enter it. Mailchimp, for example, recommends 9 words and 60 characters. Why is this important? It is important to bear in mind that more and more recipients are reading their email messages on mobile devices. And you want to make sure the subject line is visible so you get your point across.

2. Personalize (best practices for email subject lines)

Personalize your email subject line where possible, for example, when you are running a targeted campaign or sending a follow-up email. Research has consistently shown that personalization increases open rates.

3. Ask a question or solve a problem.

Engage your audience with a question that they may very well have on their minds. Provide the answer in the email message. Or tell them how to achieve business results. But refrain from sales pitches and do not over-promise…

4. Empower the recipients of your message.

Your email subject line needs to communicate an advantage to anyone that opens the email. Will they know something they did not know before? Will they have insights that put them at an advantage whether it is personally or professionally or company specific?

5. Be creative. Experiment. But keep it professional.

By all means be clever, witty, or playful with your email subject lines, but keep it professional. And applicable to the topic of your email, not just funny for funny sake. Then tie it all together in your preview text and of course email body.

6. Create targeted subject lines.

Not all audiences are alike. An email subject line that works for one audience, say architects, may not work for engineers. It is so important to gauge the angle of interest. A best practice here is to segment your audience for better open rates. Demonstrate your authority on the email subject matter in the subject line.

7. Perform A/B testing (best practices for email subject lines)

Most email service providers have that feature but you can split up your email list and test alts in Microsoft and Google mail too. Analyze results, and go with the email subject line approach that has worked for you in the past.

8. Stay relevant to the audience.

Don’t assume the recipients of your message are on the same page as you. They do not necessarily know where you are coming from. Make it clear that this is relevant to their success. Or they will not open your email message, as good as it may be. And remember, it is not what you want to say, it is what you want them to hear.

9. Use emoticons wisely.

Best practice is to avoid the use of emoticons in your email subject lines. Especially multiple ones. There is only one word for that: Overkill! But the data suggests they do increase open rates when used in context. It is not a best practice to use them to replace text, as they may not render in all email service providers. So be sure to test. 
Read this article on best practices on using emoticons in email subject lines by Klaviyo.

10. Best Practices for Email Subject Lines: Steer clear of clickbait.

They may increase your open rates, but they usually also increase unsubscribes as they disappoint readers. We hate clickbait. You hate clickbait. We all hate clickbait. It is deceiving. Just don’t do it!

11. Stay away from recipients’ spam folders.

A reputation as a spammer will land you on the blacklist.

  • Exercise caution with language that could trigger spam filters (not even when recipients are subscribed to receive email from you). Vist this HubSpot blog for a comprehensive list of words that typically trigger spam alerts. 
  • Exercise care with exclamation marks in email subject lines.
  • Don’t use ALL CAPS or 2+ Words in CAPS

12. Avoid typos.

Spell check and spell check again. It shows that you care. Not only that, typos are unprofessional and will more than likely land your email in the Spam folder too.

13. Leverage the help of an email subject line grader.

We highly recommend this. Net Atlantic has been very helpful to us at iDeal in coming up with email subject lines and ultimately, best practices! Other options include Send Check ItOmnisend, and Net Atlantic.

Best Practices for Email Subject Lines
Examples of Good Email Subject Lines

Subject Line Example – DOsComment
✅The 7 Best Trader Joe’s Finds of the Month9 Words, 42 characters, very specific, helpful – the sender has done all the research for the recipient.
✅The WORST Apps for Your iPhone’s Battery LifeInformative, compelling, problem-solving: who wouldn’t want to know that?
✅What Are the Sales Metrics That Matter?Good question. Informative. Empowering.
✅Carin, get more benefits with the Hilton Honors app.Personalized. Relevant. Beneficial.
✅Here we go againCreative. Stirs curiosity. Short and snappy!
✅How to go from 0 to 100,000 Instagram FollowersSpecific. Relevant. Helpful. Short.
✅Carin, Take this quiz to find your perfect pair of glasses!Personal. Creative. Compelling. Who could resist taking the quiz?
✅Dream Online Library, DeliveredCreative. Short. Compelling.
✅How to Grow Website Traffic by Updating Existing ContentSpecific. Solves a problem.
✅Before you write another blog post, read thisMakes you stop and think, doesn’t it? 
✅13 email marketing trends you must knowVery Specific and stirs curiosity; are you in the know or aren’t you? This better not be clickbait 😉

Best Practices for Email Subject Lines
Examples of Bad Email Subject Lines

Subject Line Example – DON’TsComment
❌Find the Surface for YouVague, irrelevant, especially coming from Microsoft.
❌New, New, NewSales-y! Unnecessary use of emoticon.
❌A Real AwakeningVague. Overstatement. Austere.
❌Top Firm Announces Plans for Reorganization & Sale of DivisionToo general – the name of the firm may have stirred some curiosity.
❌Top 24 Best Free SEO Tools 2020 That Instantly Improve Your MarketingConfusing. Long. Overstatement (instantly?)
❌Congrats! You’ve received a KrogerShopper Reward – Details InsideLanguage that could land your email  in the spam folder.
❌Urgent : NEVER_Do_THIS_During_A_Heart_AttackUnprofessional. And “Urgent” raises the spam flag.
❌BUSINESS PARTNERSHIP REQUESTVague and a Spam flag because of all caps.
❌Gear Up for 2021Vague, could be confusing and ultimately disappoint.
❌Get Rank on Frist Page of GoogleTypos and grammatical mistakes will land this email in Spam
❌You’re InvitedVague, too general.


It is not easy to come up with email subject lines that will entice recipients to open your emails. The best practices for email subject lines and examples we provided in this article will guide you to success but in the end you still have to come up with the subject line that will get you good open rates. Even the email subject line grader will only take you so far. 

You have to be creative, but remain professional. Clever, but relevant. Brief, yet specific. State the benefits of the email content, while refraining from hype. Above all, you have to know your audience. What prompts them to open emails? So experiment: Look at the metrics to see what works and what not. And make sure you stay under the spam radar. 

We hope the guidelines and examples we provided will help you obtain better results, and may the muses be with you!

Further Reading