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Best Email Subject Line Strategies to Boost Open Rates

Sep 15

Open rates are an important metric in email marketing. They’re one of the best ways to tell whether your email strategy is working or not.

Therefore, as an email marketer, your primary duty after making sure your emails get into the inbox is getting your email recipients to open your emails.

The truth is that no matter how fantastic your content is, people won’t open your emails without a compelling subject line. People judge emails by their subject lines, and that’s why a large chunk of your energy should go into crafting the perfect subject lines.

What’s an Email Subject Line?

An email subject line is the part of an email that identifies an email’s purpose. It is the first body of text an email recipient sees after your sender’s name.

By looking at the inbox messages, a recipient can tell what the email is about and decide on the spot if they want to open it or not. Email inboxes are notoriously crowded places and marketing emails are usually not as high priority as work emails. So your subject line needs to work hard to get the click.

Email Preheader Texts: What are they and why should you be bothered?

Aside from the subject line, the preheader text also contributes to a successful email campaign. The preheader text is a small line of text that appears after the subject line when viewed in the inbox.

Email preheaders summarise the email contents, giving them more context. When used in addition to the subject line, preheaders can add a significant boost to your open rates.

Mailerlite recently shared some of their best-performing subject line + preheader text combinations which generated a 50+% open rate. You can get away without writing a preheader text. If you don’t write one, your audience will see the first line of the email instead. But if you’re serious about optimising your work and achieving the best results possible, they’re worthwhile.

The best email preheaders build curiosity, have a connection with the subject line, and highlight your email’s value proposition.

Email Subject Line Best Practices

A successful email campaign starts with a captivating subject line. However, to help you achieve your main objective – boost open rate – your subject lines must conform to certain best practices.

Generally, good subject lines are personalised, concise, and devoid of spam triggers. In the following lines, we shall take a look at more specific practices for different situations.

Subject Line Best Practices for Cold Emails

Cold emails are the initial emails you send to potential customers without prior notice. Most times, people kick-off conversations in the online world via cold emailing.

Cold emailing is more difficult than most forms of communication since you don’t yet have a relationship with your audience. That’s why so many cold email outreaches fail. However, following the best practice would guarantee a higher chance of success.

1. Don’t use clickbait subject lines: Clickbait tends to get reported as spam, resulting in lower deliverability scores.

2. Keep your subject lines short: Remember, your cold prospects don’t know you, so stressing them out is the last thing you want to do.

3. Offer something enticing: It could be something about their business, a blog post, or important information. Whatever it is, make sure it creates a connection with the recipient’s goals.

Subject Line Best Practices for Sales Emails

Sales emails are emails that businesses use to promote their products and services to increase their revenue. Here are some sales email subject line best practices to follow if you want to improve your sales performance.

1. Offer value: We know you want to make a sale, but you can still do that without coming across as pushy. Australian audiences in particular hate a hard sell. Instead, your subject lines should reflect the value you bring or what the recipient stands to gain.

2. Create urgency: Urgency is very effective for getting more opens. Think limited time offers or limited quantities.

3. Write subject lines that show you care: Building relationships trumps instant sales. It might take some time to do, but your audience will become your greatest advocates if you show that you care.

Subject Line Best Practices for Donation Emails

Not-for-profit organisations generate a significant portion of their revenue through fundraising. Punchy and impactful subject lines will help ensure the best possible returns for fundraising email efforts.

1. Spark emotions: How you convey your emotions matters greatly in your nonprofit email subject lines. Donors are more likely to support you when you show vulnerability. So, instead of asking people to donate generously, tell them you need their help instead.

2. Show gratitude: Saying “thank you” makes all the difference. First, it makes people feel loved and appreciated. More importantly, showing gratitude builds goodwill and is a proven fundraising tactic.

3. Pose a question: Asking a question in your subject line is a great way to get your readers thinking. They want to know what’s next, and that bit of curiosity pushes them to open your email.


Email marketing remains the best way to create engagement and convert prospects into customers. After all the work you put in to creating your emails, it’d be a shame if nobody saw them. Work hard on your subject lines to optimise your open rate!

Unfortunately, there’s no one-size-fits-all formula for a perfect subject line; you need to keep testing to find what works for you. Nevertheless, we hope that this guide can give you a headstart. Need help with your email strategy? We can assist.