How hard can writing an email subject line be? Does it even matter what gets written?

Surely the question of whether it gets opened or binned is down to who the sender is, or what the email contains?

That’s fine when you’re emailing people you know. In fact let me just skip over to my personal email account to see what I’ve written in the subject line to my friends and family in the past week.

“Hi” (as 80% of the email subject lines in my inbox read).

“It’s me! I’m The Yellow King!” (Obscure True Detective reference. Nevermind).

“(no subject)” (...).

Glittering copy I’m sure you’ll agree. Now let’s take a look at the emails I’ve received from marketers...

“Type faster than ever with Blackberry 10” (I don’t own a Blackberry).

“Join the fight” (I don’t know what or who against and whether I fancy my chances).

“Keep your ideas fresh + Gravity FX” (lost me there).

“Christopher, who’s your Paddy?” (Paddy Power knows my name, it also knows I like puns).

“Priority booking opens tomorrow” (makes me feel special and like I’m going to get something before anybody else).

There’s clearly an art to writing a good email subject line. Out of the five examples above, three went straight into the bin without even a glimmer of attention given to it. 

The Paddy Power email aroused faint amusement, but directly underneath it was an email from asking me to sign a petition asking Paddy Power to remove its current betting on the outcome of the Oscar Pistorius trial.

I signed the petition and consigned it to the bin. I will never know what the message from Paddy Power said.

The only email I opened was the priority booking email from the BFI. Actually it’s the only marketing email I’ve opened in a month.

What’s the magic ingredient?

Is there a killer keyword that makes for an equally killer subject line that guarantees email opening, or is it entirely based on the content of the email?

Perhaps we only open emails from companies we directly subscribe too? Even then it’s only a small percentage of that company’s emails we open, so that means marketers have to work even harder to grab our attention.

Email marketing strategy is a tricky devil, with its success dependent on various factors. The time of day or day of the week the email is sent, segmentation and accurate personalisation, and the strength of the content itself, but all of that is for nothing if the email doesn’t even get opened. 

You can pump as much of your budget as you like into the content of the email as well as the system or technology you use to send them, but what’s the first thing every recipient sees before they even open it?

“Hi [name] open this email now for mega LOLS!”

Email subject lines matter. They matter a lot.

I talked to email marketing guru and regular Econsultancy contributor Parry Malm from Adestra about the importance of subject lines.

Your subject line is without a doubt the most important part of your email campaign. You get 100% eyeshare from it regardless of whether or not an email is opened.  

In terms of a ‘magic ingredient' Parry Malm goes on to state…

There is no subject line silver-bullet aside from trying out a whole bunch of words, lengths and sentiments. The dominant strategy is to try out a bunch of stuff, try out a few more things and then do it again.

Obviously by silver-bullet he means magic ingredient, but we’ll let that slide.


In the blog post 152 killer keywords for email subject lines and 137 crappy ones Malm details the study that his team carried out in isolating key ‘trigger words’ in the subject lines of 2.2bn emails.

Terms like ‘sale’ are obvious winners, as are ‘free delivery’ and ‘discount’. However, it’s easy to bombard your customer with these types of subjects and create antipathy.

Mixing up your email subjects with differing offers and content keeps your recipients on their toes and stops them from becoming bored.

The word ‘free’ however tends to trigger spam filters and according to a recent study by MailChimp, other keywords to avoid are ‘help’, ‘percent off’ and ‘reminder’.

I have a particular dislike of the daily bombardment of emails I receive from Etsy. 

Each of them carries a meaningless subject line, which may match the content within, but are hardly inspiring enough to open and as there is little variation in the two to four word buzz-phrases, therefore it just creates a blanket of white noise.


Personalisation is key to marketing.

At the simplest level it’s wise to at least get the gender correct when targeting products via email at a recipient. Age, location and point in the purchase journey are also ways to improve the chances of email opening. 

However there is nothing worse than receiving this…

“Paul check out these amazing offers!” (my name is Christopher).

“[test] check out these amazing offers!” (good one).

Personalisation means nothing if your data isn’t correct and you don’t have 100% confidence in it.

Even then, having someone’s correct name in a subject line doesn’t always guarantee success. Brands can seem ‘too familiar’: at best obsequious, at worst creepy.

For those that do open the email, personalised subject lines only work when the rest of the content is equally personalised.

Show me products based on my shopping history, or products from my wish list, not the same items that everyone on the email list is receiving. There’s no point in personal service if it just ends at the subject-line. It comes off as half-arsed.

MailChimp has discovered that although including a recipient’s name in the subject line doesn’t necessarily result in success, including the correct location of that recipient and offering deals specific to that area does.


I hate this:

Firstly, nobody likes being shouted at. Secondly, without the natural changes in capitalisation I can’t actually tell what’s being emphasised here. Thirdly, a lot of spam filters will automatically consign all caps subject line emails to the bin.

The artificial adding of ‘Fwd:’ or ‘Re:’ to trick you into thinking this is part of an ongoing conversation you’re engaged with already, doesn’t fool anyone.

I should clarify that Vogue isn’t guilty of this particular crime as the email above was genuinely forwarded by a friend, but there are plenty of examples out there.

Nice try.

Unnecessary punctuation

Multiple exclamation marks just make this bitter old man shudder. 

There are worse things though, much worse. Things that immediately get thrown in the bin if spam filters haven’t already picked them off.

Smiley faces, wingdings, even these square brackets make a perfectly legitimate newsletter look spammy:

Here David Moth highlights even more things to avoid in your email subject lines.

Subject Line Length

The general consensus from MailChimp is to keep your subject line to 50 characters or less. 

Responsys director of strategic services Jon Stanesby said that though the rules change between different industries, generally firms should avoid long subject lines.

20 to 30 characters is plenty because consumers won’t read past that and most of the wording will likely be cut off on the screen, particularly on mobile devices.

This issue is magnified on smartphones due to the small screen size, and with upwards of 40% of emails now being opened on mobile devices it’s something that marketers can’t ignore.

It’s difficult to narrow it down to a specific length as there are too many factors at play, although data from Mailer Mailer indicates that the ideal length is a rather curt four to 15 characters.

I think that perhaps short and snappy is good for emails offering discounts, promotions or other ecommerce concerns, however a longer subject line is great if you’re offering content in the form of an article or newsletter. It’s a good idea to offer absolute clarity on what’s contained, but then the more leading, questioning or teasing the subject line, the better.

Gmail’s triple-tabbed layout

As a brief aside, last year I wrote about Gmail’s new layout in 15 of the worst things to happen to the internet in 2013 in which I suggested that Gmail’s new layout is great if you’re a non-marketer but rubbish if you’re a marketer and email marketing is integral to your strategy.

Is this a correct assumption?

Mailchimp reported that open-rates dropped from 13% to 12%, which as Forbes suggests doesn’t sound like a lot, but if you’ve emailed 100,000 people, it means 1,000 fewer people saw it than normal.

I talked to Parry Malm about this and he has the opposite viewpoint:

Most email marketers burned effigies of Larry and Sergey when Gmail came out with its tabs. “They’re going to kill our jobs!” But, that’s not happened. The Promotions tab is a boon for email marketers. When people are in buying mode, they look in this tab and are ready to read your offers. This is why your subject line is more important than ever… you have less time to make an impression, but your impression is made when people want to spend money with you!

When a Gmail user is ready to click on the Promotions tab, they are expecting marketing emails, therefore will be more likely to click on the most attractive looking subjects.

In conclusion...

The research is slightly variable, especially when it comes to best practice on keywords, but each expert and study definitely points towards the same principals.

Whether offering content, promotions or discounts, just be completely clear about what your recipient can expect from clicking open. If you 'lead them on' with erroneous or disappointing content, your emails won’t get read again.

Offer a variety of email subject styles. If you’re pithy one day, go for length and detail another. If you’re offering latest products one day, offer a discount or promotion another.

As an email marketer you receive just as many emails as the rest of us. Go through your inboxes and your spam folders, and really think about what you read and why. The best exercise you can do is put yourself in the shoes of the people in your email list.

For an overwhelmingly thorough and helpful list on what to avoid, check out these 45 words you should avoid in your email subject lines.

For lots more on email marketing download our latest Email Marketing Best Practice Guide.

Christopher Ratcliff

Published 10 March, 2014 by Christopher Ratcliff

Christopher Ratcliff is the editor of Methods Unsound. He was the Deputy Editor of Econsultancy. You can follow him on Twitter or connect via Google+ and LinkedIn

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Comments (13)

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I have always been more concerned with the conversion rate than the open rate. Firstly, a conversion is more likely to be a lead, and if engineered so it will be a lead. Secondly, the open rate is misleading as many people reading on a PC or MAC may read it without opening.

Is there any advise for conversion rate? Is there a minimum or average conversion rate you would expect for example?


over 4 years ago

Parry Malm

Parry Malm, CEO at Phrasee Ltd.

Two cents, but I think email marketers focus on open rate success as a subject line strategy far too much, and should be focusing on clicks... and even better conversions. (The problem with focusing on conversions is one of sample size and short run variance - but I digress from that boring topic)

See, my theory is that subject lines are more than a "open this email" thing. What they do is they give psychological cues for action once the email is being read. If you see a subject line that says "Sale on now! Only lasts 24 hours!" chances are you'll be more likely to open AND click AND convert than a subject line that says "Come and check out our latest products, sale on now" or something.

I guess it's a bit of a Derrin Brown-style mystery as to whether it works or not. But, well, Chris was talking about a "magic ingredient", so perhaps there is a bit of Houdini action involved.

over 4 years ago



Thanks for the 'two cents'.

I take your point and understand the correlation between open and click through / conversion.

It can certainly be a mystery.

Have you ever experimented with duel-channel marketing focusing on email as one of the channels? And if so, in isolation of other campaigns.

I am interested to know which two tactics, if email is one, best create an ROI.

I have found that PR can increase email campaigns by around 2%. However, I have not had the time or opportunity to study email and advertising, email and telesales etc


over 4 years ago

Parry Malm

Parry Malm, CEO at Phrasee Ltd.

I mean, you could walk into a shop and go: "I saw a billboard for Coca Cola outside so please sell me a can." But you don't. Multichannel attribution is a dream (albeit a very sad and boring one) but is fundamentally in achievable if you expect 100% attribution. It needs to be a combo of science and intuition. Unfortunately, at least half of both are usually wrong. Lols.

over 4 years ago




over 4 years ago


Peter Johnston

“Priority booking opens tomorrow” (makes me feel special and like I’m going to get something before anybody else).

It makes me feel they're going to sell me something.

And it is usually a conference in Texas or San Francisco where the organiser can't even be bothered to find out whether I live in the US.

I complained about just this to Michael Selzner who sets himself up as a guru on this stuff. His reaction - we can't segment people.

Up against that attitude, email will always be spam.

over 4 years ago

Peer Lawther

Peer Lawther, Digital Content Manager at StepChange Debt Charity

Surprised that open rates are at 12%. We get 35-40% each month by following best practice throughout: cleaned list every month, A/B/C split testing of subject lines throughout, personalised and engaging content that appeals to what the customer wants etc. We get conversion from these when we're aiming for it but that's not the number one objective; it's retention ('loyalty' in commercial terms) over the long term.

It's not rocket science to have successful email marketing, but it does take time and effort. Some of the emails you've highlighted obviously don't have the time and effort devoted to them...

over 4 years ago


Olivia Collins

I totally agree with you, especially how subject lines can act as psychological cues making them even more important! Much of this article echoes what I’ve written in my post on how to write the perfect email subject line

Ultimately I think knowing what your audience is interested in and being honest and descriptive is usually all you need to get results, yet there are still so many companies out there using vague, misleading or just plain boring subject lines.

over 4 years ago


Krish TechnoLabs

On the best practice : you can write the subject lines pretty straightforward.

over 4 years ago


Dennis Brown

"Your subject line is without a doubt the most important part of your email campaign. You get 100% eyeshare from it regardless of whether or not an email is opened."

With ever-increasing share of mobile-opens for email (for one recent campaign we had 75% mobile-opens vs 22% desktop!), worth bearing in mind that for many recipients, the 'From' line is now given precedence over the subject...

over 4 years ago

Adam Candlish

Adam Candlish, Commercial Director at DataIQ

Does anyone have any views on the growing trend of adding graphics or what look like emoticons to email subject lines?

I have always had it on emails I find in my junk but recently I seem to get it from (what I would consider) far more reputable brands such as Sky & Premier Inn.

I felt it came across quite spammy and I thought it was a phising email posing as a trusted brand and was surprised to find that was not the case.

Any best practice guidelines on this or perhaps case studies?

about 4 years ago


Laura White, Email Marketing Executive at

Interestingly, we tested subject link length (only briefly and needs further testing) and found that the open rate was actually higher for longer subject lines. Our customers may we an exception to the rule, of course. But worth noting that "best practise" always needs putting into practice!

about 2 years ago

Parry Malm

Parry Malm, CEO at Phrasee Ltd.

Hey @Laura! Just to note, it's not really possible to test "short vs long". What you're actually testing is "less info vs more info", and length is a proxy metric.

As my company does more subject line testing than most, I can say this: we've seen often that "more info" can out-perform "less info"... except when it doesn't! :)

about 2 years ago

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