Subject line tips: how to get more opens

Most organisations use email and newsletters to inform and engage their customers and members, and with good reason: study after study puts newsletters at the top for return on investment across every communication channel. Which also means a great many others are competing for your recipients’ attention in the same inbox.

Here, the first impression decides everything — before they have even opened your message.

A good newsletter therefore starts with a good subject line, and it can be the difference between being read and being ignored. What makes a good one varies by sector, but there are general principles worth following.

The right length

There is no golden rule. Long subject lines tend to hurt open rates, but so do short, empty ones. As a starting point, a recipient sees between 35 and 40 characters on a desktop and only 20 to 37 on a phone. Tools such as Email Tool Tester’s subject line tester let you see yours on different devices.

It is also good practice to send a test to yourself and check on both desktop and phone whether the subject line is cut off. While you are there, you can check that the links work and everything sits where it should.

A good subject line creates curiosity

It is hard to be brief and still carry a sharp message that makes an individual recipient want to open.

An A/B split test on different subject lines is the practical way to find out what content — and what length — works for your audience.

Above all, keep your promise. If the subject line offers something the email does not deliver, the recipient clicks away, and in the worst case unsubscribes.

So the job of the subject line comes down to this: create curiosity, stand out in the inbox, and avoid clickbait.

Six types to borrow from

The valuable one

You give the recipient something — free content, a discount, something comparable. It sounds obvious, and it works. “Free” is not only for e-commerce; free knowledge counts too.

Example: 6 free subject lines that actually work

The intriguing one

What counts as interesting is relative, but the aim is to create curiosity and stand out. Do not be afraid to be a little cheeky. You want the recipient to stop, wonder, and want to read on.

Example: Are your subject lines beige?

The urgent one

When you want the recipient to buy or sign up, urgency (time is short) or scarcity (limited numbers) does the work.

Example: Before midnight: the free subject line guide

Or: Almost gone: get your subject line guide here

The personal one

The figures suggest an average 15 per cent lift in open rate when you use the recipient’s name. Do not use it every time, though — it loses its value fast.

Example: I have 6 tips for your subject line, Jeff

The credible one

Here you back the message with numbers or testimonials to convince the recipient.

Example: How I got 30% more opens (and you can too)

The blunt one

Sometimes you simply need the recipient to act, now. No marketing devices, no circling the point — just the message, so they know to respond.

Example: Accept our new terms here

Preheader: And carry on receiving free subject line tips

Do not forget the preheader

As that last example shows, you cannot really talk about subject lines without talking about the preheader — the short piece of text at the top of the email, shown in the preview under the subject line.

A good preheader is a second chance to earn the open, so use it to extend the subject line rather than repeat it. If you leave it empty, one is generated from your content, which usually means something from the top of the template rather than the body — a link or an alt text. We all know the “VIEW IN BROWSER” that creeps into inboxes because the sender never filled a preheader in, or wrote one too short to cover the space.

In short

Competition for your recipients’ attention is fierce, which makes standing out in the inbox critical — and the subject line is the best tool you have for it. What works varies by sector, but it is worth checking that: