How to Write the Perfect Subject Line

Email is one of the primary methods of communication, and the average working professional will receive 100 messages per day. How can your email marketing campaign stand out from the sea of others in your subscriber’s inboxes? It’s all about the subject line. Produce a great one to get your readers attention, and your emails opened.

Writing a subject line is hard. There’s a lot of pressure on the subject line to encourage your recipient to open the email. What will get more opens? More clicks? More conversions?  It doesn’t help that there’s conflicting information from all over the internet. Are shorter subject lines ideal? Or longer ones? Are personalised emails better? Argh! It’s no wonder it’s so confusing.

First of all you need to:

- Keep your subject line straightforward.

- Avoid using promotional phrases or things that look (or sound) spammy.

- Know your audience. What will interest them?


It may seem like creating a subject line is complex and sometimes intimidating, but it’s quite straightforward. Subject lines should describe the subject of the email. Wa-la! Simple.


Subject-Line Mythbusting

It’s thought that certain practices, words and phrases will make your email get marked as spam.

Spam filters will assign points to ‘spam’ words in the subject line and content of an email. If the points exceed a certain threshold then the email is considered spam and won’t make it through the filters. Spam filters are triggered for a number of reasons, but it’s rarely for one singular word. Combinations of historically spammy words will flag up those filters. And of course, your sender reputation also plays a part.

Don’t be afraid of trying:

1. All capital letters

2. The dreaded spam word: ‘Free’

3. Exclamation points (all in moderation of course)


A recent study on the open rates of over 200 million emails tried to determine which subject lines trigger recipient opening:

What Works?

- Localisation

Using geographical information can improve open rates by being personal and relevant.

- Asking a question

Subject lines posed as questions work well. Consider your recipient’s needs, interests and any other questions your content might answer.

- Keep it short and sweet

Try to keep your subject line to 50 characters or less. Shorter subject lines had more open rates than longer ones. To be very specific, emails with 28 – 39 characters had the highest click rates.


What doesn’t work (usually)

These strategies may drive quick opens, but shouldn’t be used for long term solutions for improving your marketing solutions.

- Symbols and special characters

♥ Hearts, coffee cups and starts might get your email opened, but there isn’t a definitive answer as to whether this improves or reduces clicks.


Fear of being scammed has left many customers reluctant to open emails featuring pleas for assistance or requests for help.

- Using “Re:” and “Fwd:”

This implies your email has been forwarded on from a colleague or friend, but trying to replicate this borders on deception and might damage subscriber trust.

- Using numbers

This can help quantify your message, but constant sales and promotions can lead to subscriber fatigue and loss of interest.

- Personalisation

Including the recipients first or last name does not significantly improve open rates. A recent study saw lower click through rates and open rates for personalised subject lines compared to non-personalised ones.


Get that email opened in 6 easy steps

When writing the subject line for your next email, consider the following techniques:

1. Useful and ultra-specific

Make your subject line relevant and valuable with a clear message to your subscribers.

2. Identify yourself

Is it clear to your subscribers who your email is from? Mention your most recognisable brand product, or prefix your subject line with a consistent identifier.

3. Be visually different

Make sure your email stands out visually. Consider using brackets, variations on capitalisation, phone numbers or quotes.

4. Use timely topics and urgency

A study found words used to convey relevance, or to persuade and indicate the time sensitivity of the message were most popular. Urgency works for real deadlines, but can be over used in the average inbox.

5. Call to Action:

What do you want your recipient to do? Tell them where you want them to click and what they will achieve when they do.

6. Test it out:

Split test your emails to work out which are best for your audience. And repeat!

And remember:

Set your subscribers expectations and clearly state what’s in the content of the email – don’t mislead. Don’t write your subject lines like advertisements – just tell the recipient what’s inside.

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