Mastering Cold Email: 50 Subject Lines for Maximum Impact


Crafting an effective subject line for your cold email can be the difference between getting your message noticed and getting lost in the endless sea of unopened emails.

In this article, we will learn the 50 best subject lines tailored for your next cold email campaign

Read on to learn how to optimize and test these lines for maximum impact and effectively increasing responses.

The importance of a powerful subject line
Types of Email Subject Lines
1) Catchy Subject Lines
2) Personalized Subject Lines
3) Intriguing Subject Lines
4) Informative Subject Lines
5) Short Subject Lines
How to write a cold email that actually works

The importance of a powerful subject line

If you want to increase your open rates, you need to work on your cold email subject lines. A good subject line is critical in a cold email campaign for several reasons:

  • First impression: It serves as the first point of interaction with the recipient, creating a first impression. A compelling subject line captures attention and increases the likelihood that the email will be opened and read.
  • Higher open rates: A well-crafted subject line has a significant impact on open rates. It determines whether the email will be noticed among the many others in the recipient’s inbox, increasing the likelihood of engagement and response.
  • Message relevance and interest: A compelling subject line communicates the relevance and value of the email content, showing the recipient why they should open and engage with the message.

Types of Email Subject Lines

The type of email subject line usually depends on the kind of business you have, the target audience, and the content inside the email. 

However, here is a list of main types of subject lines that you can incorporate to increase your open rates. 

1. Catchy Subject Lines

Catchy subject lines grab attention, often using humor, wit, or intriguing language to entice recipients to open the email. They are designed to stand out in a crowded inbox and pique curiosity or interest.

A catchy subject line:

Present a bitter truth instead of making extreme or offensive statements. For example: Your emails suck: Why you need to personalize
Emphasize the use of trending topics from the news or popular culture to ensure the topics are relevant and attention-grabbing. For example: Covid is killing the economy. What are you doing about it?
Use everyday phrases to immediately grab the recipient’s attention. For example: Let’s get a cup of coffee
Reference to popular culture. For example: Carpe diem the weekend sale
Use emoticons. For example: ⚠️ Last chance! Black Friday sales end in 5 hours

Here are 10 examples of catchy subject lines: 

  • “Unwrap a surprise inside 🎁”
  • “Guess What? Big News Inside!”
  • “Shh… Exclusive Access Awaits!”
  • “Don’t open this email 🙈 (Just kidding!)”
  • “Your Monday Mood Booster 😊”
  • “Psst! Limited Time Offer Inside ⏳”
  • “Find Out What’s Cooking 🍳”
  • “Ready for a Game-Changer?”
  • “Secrets Revealed Inside! 🤫”
  • “Something special just for you ✨”

2. Personalized Subject Lines

Personalized subject lines incorporate details tailored to the recipient, such as their name, company, or specific information relevant to their interests or history. They aim to establish a connection and resonate with the individual, increasing the likelihood of engagement.

A personalized subject line:

Use recipient names. For example: Maria, you need to check this out
Use business information. For example: Your website needs exit pop-ups
Referring to Current Events. For example: This tool will help with {recent company event}

Here are 10 examples of personalized subject lines:

  • “Hey [Recipient’s Name], Your Special Offer Awaits!”
  • “Exclusive Deal for [Recipient’s Company] Employees”
  • “A Personal Note, [Recipient’s Name]…”
  • “Happy Birthday, [Recipient’s Name]! Your Gift Inside 🎉”
  • “Tailored Just for You, [Recipient’s Name]!”
  • “An Offer Crafted with [Recipient’s Interest] in Mind”
  • “Attention, [Recipient’s Name]: Your Customized Plan”
  • “For [Recipient’s Company]: Your Unique Solution”
  • “You + Our Product = Success, [Recipient’s Name]!”
  • “Hello [Recipient’s Name], Here’s Your Personal Copy”

3. Intriguing Subject Lines

Intriguing subject lines create curiosity or mystery, compelling recipients to open the email to uncover more information. They tease what the email contains without giving away the entire message, motivating the reader to learn more.

An intriguing subject line:

Reference competitors. For example: {Competitor} uses {name the product}
Mention industry legends. For example: Jon Evans achieved {goal}. Let us help you do that
Create urgency. For example: Final hours: 50% off is almost over
Generate FOMO (Fear of Missing Out). For example: {Competitor} is saving 50% expense with {this tool/product}
Address Pain Points. For example: Jon, let me help you with {pain point}

Here are 10 examples of intriguing subject lines:

  • “The Untold Secret Behind Success…”
  • “Can You Handle This Revelation?”
  • “Behind the Scenes of [Topic] Revealed”
  • “Discover the Unseen: Hidden Truths Within”
  • “An Enigma Unraveled: Are You Ready?”
  • “What They Won’t Tell You About [Subject]”
  • “Insider’s Perspective: A Different Outlook”
  • “The Mystery of [Topic] Unveiled!”
  • “Unlocking the Key to [Desired Outcome]”
  • “Unexpected Insights: Dive In Now”

4. Informative Subject Lines

Informative subject lines provide a clear and concise preview of the email’s content. They communicate the email’s purpose or key information, ensuring recipients understand the value or relevance of the message they’re about to open.

An informative subject line:

 Provide industry-specific news or noteworthy updates. For example: Did you know {industry expert} won this award?
Incorporate recent trends or emerging developments. For example: You want to know the top 5 Sales Trends in 2023

Here are 10 examples of informative subject lines:

  • “Your Guide to Boosting Productivity 🚀”
  • “5 Steps to Financial Freedom Inside”
  • “Mastering Email Marketing: Pro Tips!”
  • “All You Need to Know About [Topic]”
  • “Understanding Cryptocurrency: Essential Info”
  • “Insider’s Guide: Your Path to Success”
  • “Crucial Updates on [Industry Trend] Inside”
  • “7 Marketing Strategies for Small Businesses”
  • “Everything You Should Know About [Subject]”
  • “The ABCs of Content Creation Revealed”

5. Short Subject Lines

Short subject lines are concise and to the point, typically under 60 characters. They aim to quickly convey the message’s essence, making it easier for recipients to read and understand swiftly amidst a cluttered inbox, thus improving the chances of the email being opened.

Here are 10 examples of short subject lines: 

  • “New Offer Inside 🎉”
  • “Quick Survey: Your Opinion?”
  • “Limited Time: Act Now!”
  • “Your Invite 💌”
  • “Ready for Change?”
  • “Big News Inside! 🌟”
  • “Last Chance for Savings!”
  • “It’s Time: Join Us!”
  • “Important Update 📢”
  • “URGENT: Read Now!”

How to write a cold email that actually works

With Outbound Rocks, you can create customized emails that look like you’re reaching out to a friend and automate them to save you time writing.

How does it work?

  • Create an email using custom variables.
  • Enter 3 catchy and short subject ideas to create a list of AI-generated subjects. These should be different from each other (not the same sentence rewritten 3 different ways, because the AI will do that). 
  • After that, the email subject line generator will generate a list of ideas for you. Throughout the campaign, the system will stop sending the versions that don’t work and create new versions with the subjects that work best.
  • Keep an eye on key metrics such as open rates, click-through rates, and engagement in the personalized dashboard. 

It is important to have a lot of different subjects so that the email systems (Google/Yahoo/Hotmail) see these emails as personalized emails sent from one person to another.

What are your favorite email subject line strategies? Have you written any of the above? 

Start sending cold emails or cold outreach campaigns today, request an Outbound Rocks demo today.