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Best & Worst Subject Lines Out Of 40M Emails (MailChimp Study)

By January 26, 2021 March 17th, 2021 No Comments

Back in 2016, MailChimp decided to answer the number one question new email marketers ask:

“How to write a subject line so that more recipients open my emails?”

MailChimp went into their customers’ accounts and analyzed more than 40 million email campaigns sent through the platform. 

The goal was to see what types of email subjects get the best and worst open rates. 

So, they extracted 20 from both ends of the spectrum and created a side-by-side comparison. 

According to the sample of 40 million emails, the best performers got 60-87% open rates, while the worst subject lines fell in the dismal 1-14 percent range. 

BEST OPEN RATES (60%-87%)WORST OPEN RATES (1%-14%)
1. [COMPANYNAME] Sales & Marketing Newsletter1. Last Minute Gift – We Have The Answer
2. Eye on the [COMPANYNAME] Update (Oct 31 – Nov 4)2. Valentines – Shop Early & Save 10%
3. [COMPANYNAME] Staff Shirts & Photos3. Give a Gift Certificate this Holiday
4. [COMPANYNAME] May 2005 News Bulletin!4. Valentine’s Day Salon and Spa Specials!
5. [COMPANYNAME] Newsletter – February 20065. Gift Certificates – Easy & Elegant Giving – Let Them Choose
6. [COMPANYNAME] Newsletter – January 2006 [ *|FNAME|* *|LNAME|* ]6. Need More Advertising Value From Your Marketing Partner?
7. [COMPANYNAME] and [COMPANYNAME] Invites You!7. [COMPANYNAME] Pioneers in Banana Technology
8. Happy Holidays from [COMPANYNAME]8. [COMPANYNAME] Moves You Home for the Holidays
9. ATTENTION [COMPANYNAME] Staff!9. Renewal
10. ATTENTION [COMPANYNAME] West Staff!!10. Technology Company Works with [COMPANYNAME] on Bananas Efforts
11. Invitation from [COMPANYNAME]11. [COMPANYNAME] Update – A Summary of Security and Emergency Preparedness News
12. [COMPANYNAME] Jan/Feb 2006 Newsletter12. Now Offering Banana Services!
13. Website news – Issue 313. It’s still summer in Tahoe!
14. Upcoming Events at [COMPANYNAME]14. [COMPANYNAME] endorses [COMPANYNAME] as successor
15. [COMPANYNAME] Councils: Letter of Interest15. [COMPANYNAME] Holiday Sales Event
16. [COMPANYNAME] Coffee Exchange – Post-Katrina Update16. The Future of International Trade
17. We’re Throwing a Party17. [COMPANYNAME] for your next dream home.
18. October 2005 Newsletter18. True automation of your Banana Research
19. [COMPANYNAME]: 02.10.0619. [COMPANYNAME] Resort – Spring into May Savings
20. [COMPANYNAME] Racing Newsletter20. You Asked For More…
* Study only included campaigns sent to at least 100 recipients.

Observing the Results

What’s the most noticeable trait of the successful batch? 

Well, they are kind of boring.

Yes, they lack any pushy, slimy, or salesy text. 

On the other hand, the “worst” subject lines look like paper advertisements that want to GRAB THE READER’S ATTENTION! 

Traditionally, they would be considered creative but obviously they fail to intrigue people to read the email. 

Our inbox is full of junk mail all the time and to find the stuff that matter we’ve learned to ignore anything that even hints of spam. 

Best and top email subject lines for your email marketing campaign.

How to Write the Perfect Subject Line

To get the best open rates you need to focus on one thing only – Describing the subject of your email. 

Now, I know this may sound like it’s dead-simple and the worst advice ever, but it’s not. 

First of all, set the right expectatioins for your subscribers during the opt-in process. What type of emails are they signing up for? 

Newsletters and promotions are totally different things. 

A newsletter should have the name and issue of the newsletter in the subject line. 

If you send a special promotion, express that in the subject line. 

Remember, the goal is to distance your subject from advert copywriting.

There’s a famous saying about email marketing:

The best subject lines tell what’s inside, and the worst subject lines sell what’s inside.

Your Subject Lines Don’t Have to Be Boring!

I don’t want to give the impression that if your subject is stale and uncreative you’ll get high open rates.

In this study by MailChimp, there are campaigns with creative subject lines and decent open rates. 

But the one difference seem to be in the expectations set for the emails. 

For example, conservative email newsletters are for great for products with long sale cycles. 

They use a so called “soft selling” to build steady relationships with existing and potential customers.

Use newsletters to soften your customers for the sale, or to make them feel good about your business. 

But, keep in mind that recipients that signed up for these kinds of emails won’t be happy when out of nowhere they get a flashy “%% DISCOUNT / OPEN NOW / TODAY ONLY” email. 

When writing newsletter subject lines follow the SSC formula:

  • Straightforward
  • Simple
  • Consistent

Subscribers that signed up for promotions welcome any type of secial offers from your brand. They expect a “hard sell” with e-coupons and discounts in the subject line. 

Things go wrong when a promotional email campaign is send to the entire newsletter list. 


The idea is to create different list for people interested in promotional emals. 

Ideally you should separate your promotions list into smaller, more focused categories before you send a campaign. 

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