Crafting an effective email subject line is both a skill and an art form.

Most companies are sending out marketing messages several times per week so it needs subtlety and creativity to ensure they don’t become repetitive or annoying.

This requires intimate knowledge of the company’s tone of voice and the target audience, but we can at least try to broadly identify words that help drive clicks, and words to avoid at all costs.

New subject line analysis from Alchemy Worx shows that ‘content’, ‘offer’, ‘benefits’ and ‘premium’ are four of the top five words brands can use to increase the open rate, while ‘Friday’, ‘Monday’ and ‘double’ are three of the worst performing.

It also shows that symbols and emojis can have a big impact on engagement rates.

For more on this topic, read our posts on 45 other words to avoid in your email marketing subject lines and six case studies on how to write effective email subject lines.

Best and worst words

The data shows that ‘content’ is the best word for increasing open rates (up 59% vs. the average).

Personally I find this hugely surprising as I assume that Joe Public doesn’t have the same obsession with content that has inflicted the marketing community.

It’s quite a vague term as it doesn’t refer to anything in particular (Is it video content? Written content? Are you feeling content?), but apparently consumers respond positively to it so it’s probably worth trialling in your own subject lines.

The word ‘policy’ presumably has a positive impact as it suggests that it’s an email that will contain important information (e.g. “Insurance policy documents enclosed”).

On the flip side, days of the week apparently cause the biggest drop in open rates. 

I wonder if this is in any way impacted by the sheer volume of emails sent to promote Cyber Monday and Black Friday?

Impact by industry

Looking at the impact of different words by industry, for financial services companies the words ‘policy’, ‘benefits’ and ‘premium’ apparently have the best impact.

This does suggest that the overall results are heavily impacted by results from the financial services.

Over in the travel sector, ‘holiday’ and ‘voucher’ are the most effective, while it might be best to avoid ‘departing’ or the points of the compass.

Interestingly, ‘vacation’ has a negative impact on open rates.

Best and worst symbols

The friendly snowman symbol is apparently hugely effective at encouraging people to open marketing emails (+65.72%).

In second place is a sun symbol (+20.95%), followed by a star (+10.65%).

However it’s important to consider the context in which these symbols are used.

Would including a snowman in a subject line in June really have a positive impact on the open rate?

Also, why does the black sun symbol increase open rates by 20.95%, while the white sun causes a drop of 8.03% versus the average?

In conclusion...

It shouldn’t be taken as gospel that these words will have the same impact on your own email marketing.

The open rate is influenced by a range of factors including sending frequency, time of day, day of the week, and the entire subject line.

These words should instead be used to inspire your own subject line tests so you can find what works best for your own brand and audience.

So don’t just assume that ‘premium content ☃’ is going to double your open rate.

David Moth

Published 3 February, 2015 by David Moth

David Moth is Editor and Head of Social at Econsultancy. You can follow him on Twitter or connect via LinkedIn

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Comments (5)

Pete Austin

Pete Austin, Founder and Author at Fresh Relevance

Also don't don't forget pre-headers, which are like little extra bits of subject line:

over 3 years ago


George Liapis, eMarketing at Buldoza S.A.

Nice one David, I appreciate the use of emojis a lot and have my own results that can verify your black sun vs white sun ones (the same goes to some arrows).

Have you seen any more interesting symbols? Is the full report available somewhere?

over 3 years ago

David Moth

David Moth, Managing Editor at Barclaycard

Hi George, this is all the information I have. You could maybe get in contact with Alchemy Worx to see if they have further information.

over 3 years ago

Becs Rivett

Becs Rivett, Email marketing manager at Becs Rivett freelance

Interestingly Alchemy Worx have failed to mention words like "New", "Save" or "Sale"

over 3 years ago


Dorrey Smith, CEO at Comorosa

i found this article very interesting! Now I know exactly how I should design my newsletters with my GetResponse platform. :)

almost 3 years ago

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