InsightsEmail marketing subject lines: 11 tips for best practice

Email marketing subject lines: 11 tips for best practice

Many retailers are still getting the subject lines of marketing emails wrong. Here are eleven tips for best practice, crafted from personal experience, research, and expert advice.


If a subject line is low quality, it will achieve a poor open rate, so it’s really important to get it right. We touched upon the subject briefly in our retailer newsletter experiment, but here I am going to go into more detail about best practice, because so many retailers are still getting it wrong.

The following tips are crafted from personal experience (I subscribe to A LOT of marketing emails), research by MailChimp conducted this year, and advice from the experts.

Avoid repetitive sales speak


Avoid salesy terms that trigger spam filters, such as “free”. Even if the emails don’t end up in the spam filter, words like “help” and “% off” tend to be ignored by subscribers. Avoiding garish, overly promotional phrases and instead getting smart with your copy will achieve more chance of a higher open rate.



Sending through the same subject lines that use the same predictable formula get’s really boring. Don’t repeat a specific format, mix it up a bit according to the content you are sending. New Look are really good at this:


Send out interesting, different and thought-through subject lines and content rather than just repeating information about a sale over and over again. People will start to lose interest when they release there is ALWAYS a sale on – it’s important to mix up your marketing messages.



CAPS ARE TOO NOISY. They don’t stand out for the right reasons. THEY MAKE ME DELETE IMMEDIATELY.

Do not over punctuate!!!!!!!

Also too noisy!!!!!!!!!!! See above.



Personalisation is key. On a basic level, this could be by correctly targeting gender, but other ways to effecitvely personalise include age and location – both great ways to improve open rate. It’s also important that the content beyond the subject line is equally personalised. I don’t want to receive the same generic content that everyone else is receiving, I want content that is useful for me (could be based on my shopping habits).

Deception is embarrassing and tacky

Artificially adding of ‘Fwd:’ or ‘Re:’ to trick readers into thinking that a marketing email is part of an ongoing conversation creates serious distrust.

Subject line length depends on topic


MailChimp advise that subject lines should be 50 characters or fewer, but I think it’s important to vary – obviously don’t send long rambling subject lines that don’t summarise what’s in the email, but definitely mix it up. A short nappy subject line might work well to introduce a promotion, but a longer subject line may be more useful to introduce specific content. Also important to remember: a large majority of people open emails on smartphones, which have a smaller screen size.

4 more tips from Parry Malm, CEO of Phrasee

I asked email marketing expert Parry Malm he had any more advice on subject lines best practice:

1. The main challenge with subject lines is this: a bad one affects everything else. All the time you spend on the inside of an email is wasted if your subject line sucks. So if you’re going to focus on anything, surely the subject line makes the most sense.

2. The main best practice for subject lines is there is no industry-wide best practice. Human language is incredibly complex and the only way to really nail it is to continually test, learn, and test and learn some more. And then do it again. Ad infinitum.

3. Many email marketers focus on subject line micro-tests… and they get micro improvements. Instead, test big stuff – but ensure you have a way to quantify the big stuff. If you don’t, you’re just testing for the sake of testing. You’re not going to learn anything about your audience.

4. There’s no such thing as a “bad” word across all subject lines, despite what bad statisticians may tell you. However, for your individual brand’s voice there may be bad words – and the only way you can discover this is through experimentation.





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