Lift Your Open Rates Up With Expandi Email Subject Line Generator

11 mins

Not sure where to start with your email marketing campaigns?

If you’re struggling to come up with enticing subject line ideas, it’s hard to say ‘no’ to a free email subject line generator that can give you up to 100s of sample lines you can use in the exact second.

You could have the best cold message in the world – but if no one is opening your emails, what’s the point, right?

This is why the email subject line is one of the most important parts of any outreach campaign.

To help you get higher open rates and better-performing email campaigns, below, we’re going to cover some catchy email subject line examples you can swipe, our own proven subject line template, and free AI subject line generators you can start using today.

In this ultimate guide to email subject lines, here’s what you’ll learn:

  • Why Are Email Subject Lines Important? Email Outreach Overview
  • Using AI And Marketing Automation Tools to Generate Catchy Subject Lines and Boost Your Open Rates
  • The Verdict On Email Subject Line Generator and AI Tools

PS – Looking for even more email subject lines as well as additional email marketing templates?

Be sure to join our private Facebook group, the LinkedIn Outreach Family, for all things outreach – for email and LinkedIn!

Now, here’s what you need to know about writing email subject lines.

Why Are Email Subject Lines Important? Email Outreach Overview

If your email is not opened, no one will read it.

Sounds obvious, right?


But if you’re ever uncertain where to start with your outreach marketing, the answer is obvious: subject lines.

Keep in mind most email inboxes look like this:

And when a prospect is looking at 100s of emails like these, getting their attention is dependent entirely on your subject line.

So, you need to write one that inspires curiosity or targets a specific pain point or benefit for your target audience.

We’ll show you how to do that below.

Till then, let’s take a look at how to write effective subject lines.

How to write an email subject line that gets opened

Before we cover some examples, let’s first go over some essential best practices to keep in mind when writing subject lines:

    1. Personalize your subject lines – Even simple tags like {first_name} and {company_name} go a long way as they stand out in a busy inbox.
  • Intrigue your prospects – No one likes clickbait, but simple questions do the job just as well. We’ll show you some examples of this below.
  • Use social proof – You don’t have a lot of real estate in your email subject line. So, if you can name drop a famous person or a company name, you can use that to your advantage.
  • Focus on their pain points – If you know your target audience, this can work well, especially for a targeted outreach for an agency or business owner.
  • Be straightforward – Finally, sometimes, short and specific subject lines work best. For example, even a quick “quick question, {first_name}” can get you an open rate of up to 70%!

Keep in mind if you try to do all of the above, your subject line will become too long or spammy.

So, try to focus on one angle and A/B test it to see what works best.

Now, you might wonder how long my email subject lines should be then?

Let’s take a look!

How long should my email subject lines be?

Now, this will largely depend on your industry, but shorter is often better as a rule of thumb, especially on mobile devices.

Different email marketing brands recommend other tactics. So, to save you the trouble, we did the complete research, and here’s a quick recap:

  • Use no more than 9 words and 60 characters.
  • Limit punctuation. Use no more than 3 punctuation marks per subject line.
  • Use emojis carefully, no more than 1 at a time.
  • Test subject lines to find the best-performing ones.
  • Always preview your email by sending it to yourself first.

Short email subject lines perform better because they give more space to your intro line hooks. And if your first email line is highly personalized with specific information, your leads are even more likely to click on it!

For more info on writing your email hooks, check out our full guide on how to start your emails.

Now, let’s look at how to calculate your email open rates and what percentage you should be aiming for in your outreach campaigns.

How to calculate your email open rate

As we covered in our email marketing KPIs article, your open rate is the percentage of email recipients who opened your message in the campaign.

The way they work is based on a tracking pixel within your emails. The pixel includes an invisible image displayed when the recipient opens your email.

Then, the image is downloaded from the web servers, and the metric is tracked within your outreach software.

To determine the open rates of your outreach campaign, here’s the formula:

Email open rates = emails opened / (emails sent – emails bounced)

Here, the bounced emails mean the total emails sent that could not be delivered to the recipient’s inbox. So, in other words, you’ll want that number to be as low as possible.

One way to decrease bounce rate is by using an email verification tool or going through a deliverability checklist.

So, if you want to have as high an email open rate as possible, it might be worth going over this too.

But that’s an entirely different topic. So, if you’re curious about how to avoid the spam folder and reach more contacts, check out our complete guide on how to warm up your email inbox.

What is a good open rate?

Let’s say you launched a cold email outreach campaign, A/B tested some subject lines, and averaged an open rate of 67%.

Is that a good thing or a bad thing?

First, it’s hard to analyze the success of an outreach campaign by looking at one metric alone.

You could have a high open rate but a low reply and clickthrough rate. Which would mean your leads aren’t very interested in what you have to say.

Then, you also have to consider the average industry open rate for your email marketing and your previous campaign metrics.

For example, if the open rate in one outreach campaign was 70% and 50% in the next one, it’s safe to say the previous campaign had a better subject line, based on A/B testing.

As for the industry averages, here’s what you need to know:

According to HubSpot, the total average open rate across all industries is around 20.94%.

That number can vary from 25% to 37% and higher for software and services.

But as a general rule of thumb, you should be constantly A/B testing to try and increase your open rates.

We’ve managed to hit open rates as high as up to 80% from our prospecting methods and outreach campaigns!

Another way to generate subject lines that get a ton of clicks is through AI-powered tools.

Let’s take a look at how.

Using AI And Marketing Automation Tools to Generate Catchy Subject Lines and Boost Your Open Rates

Coming up with unique subject lines for A/B testing can be tricky.

Especially if you’ve already run through the standard 10+ lines and templates everyone uses.

When that happens, using an email subject line generator can be a great way to breathe some fresh air into your outreach campaigns.

What are email subject lines generators?

An email subject line generator is an AI tool or service that helps you generate lines for your outreach campaign.

They offer multiple options, angles, and types of subject lines, based on the content of your email and your overall objective.

The purpose of your subject line is almost always to get your audience to click on the email.

But the type of message you’re sending can vary.

For example, you could be sending a follow-up email to stay on top of your leads or a re-engagement email to heat up cold leads and contacts.

Based on the objective, your subject line will differ as well.

Keep that in mind the next time you’re using AI tools.

While they can provide you with some enticing subject lines, they’re not always perfect. And you might want to do some manual finishing touches if you feel they’re not entirely up to par.

Now that you know how to write your subject line and how the AI-powered tools work let’s look at the top 5 email subject line generator tools you can start using today.

Top 5 free email subject line generators to boost your open rates

  1. ActiveCampaign email subject line generator


ActiveCampaign is an email automation platform for all things email marketing, CRM, customer experience, and more.

But they also offer a free, nifty email subject line generator that lets you select different keyword categories (benefit, topic, pain point) for your subject line based on your main keywords.

Once you click Generate, the tool gives you 4 free subject lines, which you can then refresh for even more suggestions.

The best way to illustrate is with examples, so let’s cover each keyword category.

Benefit subject lines:

With the keyword “quality leads,” its generated suggestions include:

  • Why I turned down quality leads.
  • For when you need quality leads.
  • 15 things you didn’t know about quality leads.
  • Quality leads! NOW!

Topic subject lines:

With the keyword “LinkedIn automation,” its generated suggestions include:

  • LinkedIn automation.
  • Long live LinkedIn automation.
  • Now you can have LinkedIn automation without the work.
  • How to do LinkedIn automation like a boss.

Pain point subject lines:

With the keyword “unsafe automation,” its generated suggestions include:

  • The uncomfortable truth about unsafe automation.
  • Sick of unsafe automation?
  • How to fix unsafe automation like a boss.
  • How to fix unsafe automation.

As you can tell, many of these are based on pre-loaded templates, and the AI tool simply places your keyword automatically.

And the quality is certainly mixed.

However, with some manual touches, their angles can be improved and give you a better tip in your outreach.

And that’s another critical thing to keep in mind when using AI marketing tools.

While the quality delivered straight away sometimes isn’t the best, it can be a great starting point.

So, instead of racking your brain trying to come up with subject line angles on your own, you can use these AI tools and edit instead of writing personalized email subject lines from scratch.

Now, let’s look at some more free tools.

  2. Keap

Keap is another email subject line generator free tool you can use to capture your audience’s attention with various email types.

Here’s how it works:

First, you select the type of email message you’d like to send, which can include:

  • Newsletter.
  • Re-engagement.
  • Follow-up.
  • Promotion.
  • Resources.
  • Registration.

Then, you define who’s getting the message within the tool:

  • Your target audience.
  • Category of interests or keywords.
  • Big pain point they want to avoid.

And finally, you generate subject lines.

Here are some subject line examples for a cold outreach email with this tool:

  • Here are a few ways to make marketing a breeze.
  • It’s been a few days. Ready to generate leads?
  • There has never been an easy way to generate leads unless you count…
  • Can we help you with any marketing questions?

The verdict:

Many subject lines generated by Keap are too long or unnecessarily complex.

However, Keap can give you some solid starting angles to edit and build upon like many AI tools.

With some experimentation, you could develop enticing subject lines that are hard to not click on.

  3. Salesblink cold email subject line generator

Salesblink provides a simple, barebones approach to generating subject lines for a cold outreach email.

As you can see, all you have to do is enter the service you provide and the recipient’s company name.

From there, through a mix of ready-to-go templates, Salesblink will generate subject lines accordingly.

One thing this tool does differently from others, though, is that it also gives an open rate percentage. It is presumably based on averages from different outreach campaigns.

Here are some examples of the better subject lines this tool generated with the keywords “LinkedIn Outreach” service for “Microsoft”:

  • Don’t Open This Email (67% Open Rate)
  • You’re not alone! (63% Open Rate)
  • I was right – and that’s not good for you (37% Open Rate)
  • schedule call for LinkedIn outreach (37% Open Rate)
  • LinkedIn outreach for Microsoft (39% Open Rate)

These lines aren’t very personalized and are more typical for sales emails that jump into pitching you straight away.

Which is to say, they could use a round of edits to be usable.

  4. Encharge

Encharge is a free AI-powered email subject line generated based on GPT-3 technology.

Meaning they use a protocol developed by OpenAI to scrape the internet and predict human-like word formulations to produce enticing email subject lines.

And another thing they do well is that Encharge gives you a lot of choices for the email tone, ranging from appreciative to urgent.

Let’s take a look at some examples with the following keywords:

  • What is the email about – safe LinkedIn outreach.
  • Company –
  • Tone: Inspirational.

Here are the subject lines the AI tool generated:

  • Reach Out and Touch That [expert you admire]
  • Time To Grab Your Signature
  • Isn’t That What You Came Here to Do?
  • What would you do with 50k?
  • The Easiest Way to Start Generating New Leads
  • How I Met Marketing Automation

On their own, they lack a sense of urgency or curiosity.

Though, with some edits, they can definitely be improved.

This seems to be a trend with many of the AI-writing tools…

See our full verdict on these AI-writing tools below.

Now, let’s look at one last tool before we wrap up.

  5. Portent

Last but not least, Portent is probably the most straightforward tool on this list. All it needs is only the subject of your general message or solution.

Though that’s a bit vague, and sometimes, you’ll need a few tries to get a sense of what kind of keyword category it works with best.

Once you get the hang of the tool, this AI-powered tool can come up with some creative marketing emails.

Here are a few examples with the subject “LinkedIn”:

  • 5 Things You Don’t Want to Hear About Linkedin.
  • 15 Unexpected Uses for Linkedin.
  • How Linkedin Could Get You on The Today Show.
  • The Insider’s Guide to Linkedin.

Many of the subject lines generated by this tool feel like they would be better for content marketing and blog posts.

But with a few rounds of edits, you can optimize them for cold email outreach and get higher open rates.

Finally, before we sum up…

The Verdict On Email Subject Line Generator and AI Tools

One thing all of the above AI tools have in common is that they’re not personalized.

They can create personalized email subject lines, but they’re not very unique or specific even then.

And when you’re doing outreach, you’ll want to clarify that a human, not a robot, wrote your message.

Many AI-powered tools lack the charm or branding necessary in marketing.

However, one significant upside they bring to the table is that they save a lot of time.

Most of these tools indeed use pre-written templates.

But it’s better than nothing!

If you’re having a hard time coming up with fresh ideas on your own, you should strongly consider giving them a try.

While many subject lines the tools generate might not be used directly, you can always manually edit them, so they’re more personalized and on point for your brand!

So, email subject line generators – while they’re not perfect, as long as you know how to use them, these AI-powered tools can save you a lot of time when starting from scratch.


Hope you found this ultimate guide to email subject line generators helpful!

Let’s go over some of the most frequently asked questions before concluding.

  • How do you write a catchy email subject line?

To write a catch email subject line, you need to include some conversion-driven elements that compel the recipient to click on the email. Such as:

  • Scarcity and fear of missing out.
  • Personalization.
  • Relevant pain points or benefits.
  • Curiosity and simplicity.
  • Relevant and straight to the point.
  • And more.
  • What are the best subject lines for emails?

We’ve covered both AI and human written subject lines in this guide, but from our experience, some of the best subject lines that generated up to 80% open rates were simple lines like:

  • Quick question, {first_name}
  • Hey {first_name}, is this relevant for {company_name}
  • Is (solution) relevant for you, {first_name}
  • Quick question on (topic)
  • Does this warrant a collaboration?
  • What is subject line in email example?

The subject line is the first line of an email the recipient sees once they receive your email. The subject line’s objective is often to get people to click on the email. So, make sure it’s optimized for your target audience and doesn’t include any suspicious words that might set off the spam filter.

Looking for even more info on writing a strong subject line that gets high open rates?

Be sure to join our private Facebook group, the LinkedIn Outreach Family where we discuss the latest email and LinkedIn outreach practices to get you quality leads.

Now, if you’re looking to set up your first email outreach campaign with highly enticing subject lines, be sure to sign up for a free Expandi live demo or gain access to a free, 7-day trial to automate your sales outreach now!

Whether it’s LinkedIn or email (or both), you can set up custom outreach campaigns and reach your target audience on multiple channels with additional automated follow-up flows.


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