Can Artificial Intelligence Write Better Email Subject Lines Than Humans?

By paul@pr2020.com (Paul Roetzer)

Can AI write a better subject line than an actual person? Probably. Brands like JOANN have had a 10% increase in email open rates, all thanks to AI.

Unless you’re an expert email marketer, coming up with brilliant subject lines every time can be tough. This is especially true if you’re sending personalized emails multiple times per week.

Plus, you may need to write several subject lines and run split tests to find the best. This is time-consuming!

This post will explore how AI works with email subject lines and why you should get inspiration from AI when writing email subject lines. You’ll also learn about some of the best AI email subject line generators.

How AI Works With Email Subject Lines

Many AI technologies are still in their infancy. They look good on paper but haven’t reached their potential. That said, there are other AI content generators that have advanced rapidly to become game-changers.

It’s this second group that is driving the AI explosion we’re seeing today. Two technologies, in particular, have driven AI progress:

Natural language processing (NLP)
Natural language generation (NLG)

NLP is when a machine “reads” text. It turns that text into code a machine system can then interpret. NLG is when a machine uses that code to generate its own words.

These technologies are found in AI-powered marketing tools like Acrolinx, which uses NLP to assess your content and recommend improvements. One other major use case enabled by NLP and NLG is, you guessed it, writing email subject lines.

Besides saving time, another benefit of AI tools is that developers train them on email engagement using a large amount of data.

These data are based on email best practices, enabling the AI tools to create bias-free subject lines that could cause high open rates.

As Parry Malm puts it, “When humans make choices, they inject their own experience, thoughts and beliefs.” This can cause bias and make us opt for subject lines that may not be the best.

But AI is free of bias, and it’s trained using clean data. “AI output is based on pattern matching, which is invisible to the human eye and devoid of cognitive biases that lead to poor decisions,” Parry adds.

Now, let’s explore some of the best AI tools for generating email subject lines.

4 AI Tools for Generating Email Subject Lines

I tried most of the AI email subject line generators and barely found those that made the cut. Some of the output didn’t follow best practices, as the subject lines were long.

Below are four of what I consider the best AI email subject line generators in 2023.