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RE: Top 9 email tips

Five words (maybe 6). 20 characters (maximum 30). And a few seconds before your recipient's thumb swipes past the email that likely took you hours to craft.
Image credit: Muhammad Ribkhan from Pixabay.
Image credit: Muhammad Ribkhan from Pixabay.

Being able to catch someone’s attention in one of the most cluttered, noisy communication spaces in our modern lives – the Inbox – is not just based on luck, but rather the interplay of timing, creative art and behavioural science. After all, over 100 billion emails are sent every day. And sometimes it’ll feel like they all come to you.

Over the past decade, I’ve helped marketing teams send emails to databases with millions of people and, together with insights from Everlytic, I’ve benchmarked industry trends when it comes to all things email marketing: open rates, click-through rates, data segmentation methods and the all-important timing success of delivering your message.


Persuading someone to stop, pause and click on your email is no easy feat. So, the principles of behavioural linguistics – nudge-based communication – are handy here. Successful, intelligent nudging is achieved when the “3 Cs” come together:
  • Content (the type of nudge)
  • Context (type of customer)
  • Contact (how and when the nudge is delivered).

In the same way that we make quick judgements about people based on their first impression, the email subject line that hits our inboxes needs to impress. Or, at least, stand out. The words you choose for your subject line will have a big impact on whether your audience decides to give you their most valuable commodity: their time.

No matter how innovative, exciting or rewarding your campaign is, if the people you send your communication to don’t open the email, it’s all in vain.

In my experience, subject line crafting is often an after-thought. Days, if not weeks, are spent on the mailer content itself – the wording, the hyperlinks, the call-to-action buttons, the visual content, etc. – yet on the day of mailer dispatch, there’d always be a scramble for the subject line.

To help you avoid this pitfall, here are some of my top tips for crafting that perfect subject line, every time.


1. (Obviously) Keep it short


Most people access their mails using a mobile device so the length of your subject line really matters. Too long and it’ll cut off in preview view. Aim for five to seven words, at 25-30 characters so that as your reader scans their inbox quickly, your mail is in full view.

RE: Top 9 email tips

I’d recommend trying out the occasional one-word subject line. If the average length is six words, this really stands out visually in an inbox. Don’t forget that you have the preview text to help support your subject line message.

2. Avoid the spam filters


Spam filters are becoming more and more advanced and they’re important tools to help filter out trash from treasures. If you’re aggressively sales-y in your subject line, it’s likely this will be marked as spam and you’ll miss the opportunity to reach your consumer.


Avoid ‘loud punctuation’ like multiple exclamation or question marks and all-capital letters. Words like “free” and “buy” are also red flags to a spam filter, so minimise these where possible. You can use a free tool to test your proposed copy to make sure it scores high enough.

Another tip is that if you’re still sending your mails from “", it’s time to change that. Not only will this likely get classified as spam, but it immediately sets the tone as less personable to the receiver. The best impression you can make on your customers is that they’re working with an individual one-on-one, not an entire impersonal business.

3 . Have fun with language


You know all those high school language classes you suffered through? Let them come in handy now.

Alliteration, onomatopoeia, assonance, repetition, puns, metaphors, pronoun usage etc. are all great linguistic tools for creative writing and, more importantly, persuasive writing. Rhyming is particularly effective and alluring (known in behavioural linguistics as the “rhyme-as-reason” cognitive bias) because we’re attracted to rhythmic sounds and believe content to be more truthful if it rhymes.

The sentence type you use is also important. Questions (interrogative type) help to focus your readers’ attention and pique their interest. Using questions draws in your reader and encourages them to find out more by opening the mail. Commands (imperative type) grab attention and are useful if you have a strong call to action in your subject line.

For your call to action, start with action-oriented verbs. Actionable subject lines inspire higher click rates because there is an inherent compulsion to follow the instruction and to picture yourself in the experience. Order from Debonairs this evening” works better than “Debonairs has new pizza on the menu”.


4. Get personal and time it right


One of my favourite email subject lines arrived in my inbox at 5pm on a Friday – on payday. And it enthusiastically addressed me with relevant contextual information and offered me an easy option for dinner. I ordered Mr Delivery that night (thanks Megan!).

RE: Top 9 email tips

Adding a personal touch (caution: make sure your data is correct) helps build rapport with the reader and is linked to higher click-through rates. If possible, segment your data and bring in whatever personalisation you can that is relevant. This includes name, age, company, location or gender (don’t get stereotypical though).

If your data analytics aren’t 100%, rather draw on personal pronouns “you”, “your’, “we” and “us” to achieve a similar intimacy.


Getting the timing right is a science within itself. Food delivery brands have it easier than most with time periods where they can strike and offer the appropriate restaurant for the time of day. In the United States, where happy hour drinks specials are commonplace, 6pm emails with the subject line "Where to drink wine now” are successful.

To establish your brand as relevant and even as a thought leader or industry expert, using trending topics (national holidays) and timeous headlines (reflecting current events) helps establish authority and persuades people to read your content.

5. Incorporate behavioural science


From gain framing to loss aversion, there are a host of behavioural biases and heuristics that you can draw on to make your subject line more ‘nudgey’. One of the most powerful principles is scarcity: people have an inherent fear of missing out on opportunities and if something is framed as limited (with a time deadline, limited quantity or limited offer availability) this creates a sense of urgency that encourages readers to prioritise your email.

That said, don’t overuse this tactic. Save the scarcity and urgency for when the occasion genuinely calls for quick action or else you’ll risk losing trust with your reader in future.


Another behavioural technique is social proofing. This is where people are more likely to do what they think other people are doing. So if 85% of your fellow *insert brand* members are doing *insert call to action*, you make a compelling case for why they should do it, too.

It’s a fine balancing act, though. As much as we’re persuaded by herd mentality, we also want to feel special. The psychology of exclusivity is a powerful motivator so subject lines that reference “exclusive offers”, “private invitations” and “VIP treatment” can go a long way in converting better on your emails.

My favourite example of this? From a local fashion retailer, the subject line: “You deserve the best.”

And what would an exploration of behavioural science be without mention of incentives? In behavioural economics, reciprocity is a social influence tool where people feel compelled to reciprocate.

So, if you’re offered a gift or special offer in an email, you feel compelled to reciprocate in some way, which can mean giving up your time and engaging more in the mailer. Plus, everyone loves getting a deal or a freebie so if you can pair your content with an incentive, mentioning this in the subject line is alluring.

Remember those spam filter red flags, though.

6. Make it visually appealing


Unexpected words like “uh oh” and “oops” are not only great for a conversational tone (if that fits your brand’s voice), but are also visually appealing in how unexpected they are. I’m also a fan of using the prefix “RE” for the odd mailer. This is eye-catching because it signals familiarity like you’re in the middle of a discussion that needs to be continued, rather than a cold-call mail.

These days, visual content in your subject line means one thing. Emojis. This used to trigger spam filters immediately, but have become accepted now and you’ll see more and more brands trying them out. Some research has shown that leveraging emojis and symbols in your subject line can bump up your open rates. This example, in particular, showed a 300% increase in open rate:

Sales ⬆, Refunds ⬇, Retention ⬆

The pattern and repetition here are attention-grabbing and the succinct copy clearly communicates the mailer’s value proposition.

7. Use numbers


Linked to the previous tip, numbers help copy to look appealing in an inbox because of the text/numeral differences. Subject lines with numbers stand out for the same reason that one-word subject lines or unusual punctuation do – they are visually jarring so help to stop your reader’s thumb from scrolling and dismissing.

Using data and numbers is a great way to get your emails noticed, demonstrate a clear and straightforward message about your offer and set the right expectations. A tip when using numbers is to opt for slightly unusual ones. A list of uneven seven, nine or 11 items is less common than normal multiples of five, 10, 15 so sticks in the mind longer.

My favourite number subject line was a timely example sent by Discovery Vitality after their ambassador Wayde van Niekerk broke the 400m world record. “You have 43:03 seconds to read this” was a trifecta success in that it had reference to a trending topic combined with principles of visual appearance and drove urgency.

8. Start to tell a story


Storytelling is the most human way to get attention. A fundamental characteristic of humans is that we look to the behaviour of others when making decisions (as discussed in tip five about social proofing).

RE: Top 9 email tips

By including an individual’s success story or part of their experience in the subject line, you show the people behind your product which helps to leverage interest in your mailer. Sleekgeek, an online platform encouraging healthy lifestyle goals, uses this testimonial technique well in their subject lines.

9. If at first, you don’t succeed…


Test, test and test again. Give yourself a time buffer so that you can A/B test your subject lines. I was once advised to come up with 10 subject lines, whittle these down to five and then test these five for at least a week before dispatching the mailer to the rest of the data set.

Sometimes you won’t have that time luxury, but where you can, test your highest-stakes subject lines and then tweak the wording according to what you find.

Ask yourself: What works best for your readers? Long or short subject lines? Including numbers or not? Questions or commands? And when should you send your mail?

To find out what time of day is best for your send, segment your list into two or three equally-sized groups and send the same copy of your email during different times of the day (morning, afternoon and early evening).

Track which version gets the highest open rate to guide your future sends. As a guideline, the table below shows some of the most successful send times across various industries. You can use these as a baseline and experiment to find the best time for your brand and specific audience.

IndustryDayTime
Accommodation/hospitalityMonday4pm
Animal-relatedMonday9pm
Child-related/educationMonday3pm, 4pm
Financial advice/bankingMonday6pm
Nutriton-relatedSunday8pm
Fitness-relatedSunday10pm
MedicalMonday7pm
Charity/NPOTuesday8pm
Real estateTuesday8pm

Everyone wants a clean inbox. If your emails aren’t being opened, they’re not getting seen. You no doubt have great, relevant content to share with your readers, but you’ll first need to prove it through your subject line.

About Leigh Crymble

Leigh Crymble is a behavioural linguist and language practitioner and founded BreadCrumbs in 2019 - South Africa's first Behavioural Linguistics firm that is rooted in behavioural theory and combines sociolinguistics, psychology and marketing principles to create personalised and persuasive communication.

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