What makes a good email marketing subject line?

The average user receives 416 commercial messages a month (Return Path).

Your subject line is key in making sure you stand out from the crowd, in making sure you're seen by your customers and in making sure they open your email.

Here are our top ten tips for writing the best subject lines:

1. Keep it short and sweet

If you think about it, you've probably only got 2 seconds to grab their attention and get them to open the email.  Keeping it short and sweet is the key, if your subject line is going above 50 characters then it's too long and will be cut off, especially on mobile devices.

2. Be relevant

It sounds obvious but tell your customers what they're going to find inside the email. Don't tell them they're going to get free beer just to encourage them to open it when your email is really about financial services, people will feel cheated and you'll lose their trust. Keep it relevant and use a compelling call to action, and you won't need to use trickery.

3. Ask a question

We find that emails with subject lines that are questions typically tend to see better performance. Don't be afraid to ask a question if it's appropriate - it's a great way to frame the content of your email and to set the scene for encouraging a click-through.

4. Be personal

Talk to your customers directly and make them feel part of something.  The use of both 'you' and 'your' see good results for our clients. But be wary of using first name personalisation in your subject lines as people may be suspicious of this.

5. Be persuasive

This is your chance to persuade your customers to open. Be wary of over-promising (will an email really change someone's life?) but if you have a sale or are running an offer then draw people through by highlighting it in your subject line.

6. More than a newsletter

Email marketing has moved on from the days of the humble newsletter. Even if your content is primarily news driven, it's going to take more imaginative language than 'August's Newsletter' to get people to open your campaign.

7. Be time sensitive

Creating a sense of urgency is a great way to get people to open. 'Last-minute sale' or 'Book before midnight' are two examples. By adding a time element to your subject line it makes your customer act quicker and they are more likely to open

8. Say who you are

This should be done as standard in the 'From' address so your customers know who they are receiving the email from. Using a name your subscribers recognise will re-enforce your identity and help cut through the noise.

9. Stay on brand

Although it may not result in immediate banishment to the junk folder, we recommend that our clients avoid overuse of block caps and excessive punctuation as this can trigger subscribers to report abuse. Consider your reputation before sending a subject line that looks spammy.

10. Test it

If you're unsure of what subject line is going to work, then test it. You can run an A/B split test to a sample of data and then use the best performing subject line to go out to the rest of your database.

Crafting a subject line should always be well thought out and planned. They are integral to successful email marketing. There is no magic formula because every business is different. However, if you use our tips, then analyse your use of subject lines over time to see what works for you, you'll see much better levels of engagement and have far happier customers.