Email is a key component of almost any marketing strategy, whether it’s to prospects, customers, B2C or B2B. You have a chance to communicate directly with someone who has already connected opted-in to your marketing, clearing the first major hurdle. The subject line will make the difference between being ignored, seen as spam, and even unsubscribed from, as opposed to getting a customer to open your email and genuinely engage with your content.

Here are 12 simple principles to keep in mind when crafting your email subject lines, to increase your open and engagement statistics – meaning more effective marketing and communication.

1. Keep it short and to the point – ideally under 5-7 words. 

Not only will mobile clients cut off anything after that, but with all the marketing emails that we all receive, readers will make a snap judgement at a glance, meaning you have a very short space to get their attention.

2. Avoid using all caps, instead opt for Sentence Case.

Already our standard across Rezdy, sentence case feels more like how a real human would communicate with another. Think how many times you have used all CAPS or Title Case in an email subject between you and a colleague – likely not much. It will feel much less personal and more like advertising.

3. Address it from a real person.

While you don’t want to be dishonest, sending from a real name increases your chances of the customer opening – Often you will see better engagement using ‘Max from Rezdy’, or the Rezdy Account Management team rather than simply ‘Rezdy’. You might have noticed some examples of this in your own inbox.

4. Personalise.

A well-known principle throughout modern marketing, using the person’s name, business, location or something else relevant to them will show that you know who you’re talking to and feel less like a broadcast spam email.

5. Ask a question.

Asking a question can create engagement and a sense of conversation with the customer, bonus points if it is something they have already asked themselves, or once they read it, makes them truly think about the answer.

6. Answer a question.

The more confident sibling to the above, if you know what questions your customer base is already asking themselves – show them you have the answer. For example, “This is how you prepare to reopen”, or “3 actionable steps to improve SEO”

7. Test wherever possible.

Often our assumptions can be incorrect, and within email if it is possible to test variations, it’s always a good idea to do so – for example positive versus negative (eg. “5 tips for better marketing” vs “5 common marketing mistakes”, or question versus answer (“Is your SEO up to scratch?” vs “3 steps to improve SEO”)

8. Use numbers. 

Using numbers and lists within email subjects has been shown to increase curiosity and engagement – if the context is relevant. For example, “6 ways to improve customer reviews” will be strong, as opposed to saying “Thousands of customers are waiting for you”.

9. Start with an action.

As long as it doesn’t sound too commanding, beginning the subject with an action can immediately communicate your intention to the customer, for example “Focus your marketing budget where it works”

10. Consider using Emojis in the subject.

While it may not fit some brands, particularly in a B2B context, emojis have been shown to increase open rates in testing. Be aware though that the tone matters, and it’s important not to make light of a serious topic. Also worth noting that this is stronger while it’s a novel approach, and will likely diminish over time as it becomes more widespread.

11. Use the Preview text wisely.

Seems obvious, but many businesses still don’t make the best use of the preview text (the lighter text that appears after the subject line). It should provide context and secondary information to the subject itself, otherwise it will jump right into the body copy and feel disjointed

12. Listen to the pioneers that have gone before you.

Marketers have been testing email subject lines for years, and there are tools and keywords that have been tried and proved. Of course every brand is different, and you’ll need to adapt to suit your own, however free tools such as Coschedule have a quick scoring test with many of these rules built into its system. They also have a handy list of ‘Good’ and ‘Bad’ keywords compiled through hundreds of tests.

Plus, get your Email Marketing Best Practice Checklist here

Beyond subject lines, we’ve got the key habits for email marketing here for you. Print it off and keep it in the office, so you’ll always be able to quickly ensure your emails have the best chance of connecting.




Written by – Max Harris Brassil – Marketing Manager – Customer Growth, Rezdy

Max is a lover of all things travel & is always on the lookout for the best local tours and experiences. With a background in loyalty & email marketing, Max is passionate about working with Rezdy customers so that their business reaches the greatest success.


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