Email Subject Line Generator

Generate subject lines for your next email campaign.

1. Input

Input a keyword or topic.

2. AI Writer

Frase AI will perform some magic to write subject lines.

3. Output

Frase will output email subject lines; copy and paste into your document.

Take AI-powered content creation to the next level with Frase ✨

Generate compelling email subject lines that boost open rates using our AI tool.

Why are email subject lines so important?

According to OptinMonster, 47% of email recipients open your email solely based on the subject line.

And yet email marketing is still one of the most effective ways to reach out to customers and prospects.

But sending emails without a good subject line is a sure way to get them ignored or deleted.

Email subject lines are often the difference between getting opened and being deleted. To increase your response rate, you should optimize your subject lines.

How the Email Subject Generator Tool works

  • 1. Input: Input a keyword or topic
  • 2. AI Writer: Frase AI will perform some magic to write an email subject line for you.
  •  3. Output: View the email subject line ideas we generated. Click the copy icon to paste your preferred option into your document.

How to write an email subject line with these 7 tips

Relevant, personalized, anticipated

In Seth Godin’s Permission Marketing book, he coined the 3 tenets of successful email marketing.

1. The email should be relevant to your readers.

Frase doesn’t send website conversion emails to customers who use our content creation and writing tool.

2. Personalize the start of the email body with “Dear Firstname,” however, many email marketing solutions allow you to insert the subscriber’s first name into the subject line.

Campaign Monitor reported that emails with personalized subject lines get a 26% boost in open rates.

When was the last time you waited impatiently to receive an email?

Not very often.

3. Anticipation is based on a hook, a tease to reel you in and make you want to read more.

If you want to build anticipation in emails, you need to make something interesting as bait to catch your reader’s attention and intrigue them into finding out what’s inside.

That’s why a good subject line is crucial.

Ask questions

Questions make good subject lines because people want to know the answer.

People love to find out the answers to questions, and that’s why asking questions in your email subject line is so powerful.

Offer value

Provide something valuable in exchange for the time invested in opening your email newsletter.


When you create urgency in your subject line, the open rates increase.

Use this technique sparingly, though, as sending too many emails with urgent subject lines could be perceived as desperate.


Considering  21.33% is the average open rate for email newsletters across all industries, using curiosity can bolster your email campaign metrics.

Humans are curious by nature, and we’re wired to seek out new ideas, new products, and services.

Sleeknote curated a list of the top 7 curiosity subject lines that you can quickly adapt to suit your business and email campaign.

  1. This is what your neighbor is doing
  2. Don’t Open Until After
  3. Deal Enemy #1
  4. Black Friday Secrets Revealed
  5. We’ve been waiting months to announce this
  6. Does your ghee come from happy cows?
  7. We don’t normally do this?

Subject line length

According to 99firms, 85% of users use smartphones to access email.

So aim to keep your subject lines to 6-8 words or under 50 characters to cater to smaller screen sizes.

A/B Testing

Email marketing tools such as ConvertKit offer an A/B testing feature to find the best subject line.

  • ConvertKit will send one subject line to 15% of your recipients and another subject line to another 15% of recipients.
  • After a few hours, they’ll select the winning subject line based upon which one resulted in the highest open rate.
  • They will send the winning subject line to the remainder of your email list.

Types of Email

So, what types of emails can you send using our free email subject line generator tool?

Cart Abandonment Subject Lines

What is a cart abandonment email?

It’s when someone buys something online but doesn’t complete their purchase.

These emails aim to get the customer back on track and encourage them to finish their order.

You can also increase conversion rates by adding a discount code at the end of your email subject line.

Customer Retention Subject Lines

If you have customers who haven’t opened your emails in a while, it might be worth trying a different approach.

Instead of just reminding them about your product or service, try offering them some exclusive content.

For example, you could provide a free tutorial video series if you sell software. 

Cold Sales Email Subject Lines

Cold emails are unsolicited messages sent via email to potential leads.

Here are 5 tips to help you write effective cold email subject lines:

Use a conversational tone

  • Avoid jargon
  • Be specific
  • Keep it short 

Follow Up Email Subject Lines

Follow-up emails are sent after someone has interacted with you, your website, or purchased something from you.

These emails could be part of an email sequence, outreach email campaign, or cold sales emails.

Onboarding Email Subject Lines

An onboarding email is sent after a user signs up for your product or service.

It’s designed to help new subscribers understand how to use your solution. 

Product Launch Email Subject Lines

A product launch email is sent right before a new product goes live. It’s used to introduce people to your brand and let them know what to expect once the product launches.

Here are 5 tips for writing a successful product launch email:

  • Make sure your first sentence is compelling.
  • Use bullet points to make it easy to scan.
  • Include a call to action.
  • Keep it short and sweet.
  • Add value. 

Re-Engagement Email Subject Lines

A re-engagement email is sent to existing customers who haven’t interacted with your company in a while.

Sending re-engagement emails can increase sales because it shows that you care about your current customers.

It also gives you more time to build relationships with potential customers.

Here are 4 things to include in a re-engagement email:

  • Thank you message.
  • Offer a discount code.
  • Share a blog post or article.
  • Provide additional information.


Yes, you can use this tool for free!

This tool was created to give you a taste of AI-powered content creation.

Start a Frase Subscription to gain access to more features.

Not ready to subscribe yet? Learn more about Frase, or schedule a demo.

Frase uses a proprietary AI model trained on billions of web pages from across the Internet. Think of Frase AI as a large-scale autocomplete system – feed it some text and it will predict what goes next.

Frase AI can be trained and fine-tuned to perform specific tasks. This is accomplished through “AI Templates”, such as:

No, Frase uses its own proprietary AI model. This allows us to provide more flexibility, custom features, and competitive pricing.

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