Best Practices for Cold Emailing Subject

Best Practices for Cold Emailing Subject Lines

“Don’t judge an email by its subject line”—said no one ever.

When it comes to cold email campaigns, subject lines can make or break your efforts. They are the most prominent element in your recipients’ inboxes, drawing immediate attention. This split-second decision—whether to open your cold email—depends largely on your subject line’s effectiveness.

The Importance of Subject Lines in Cold Emails

Your cold email subject line is the gateway to your email content. A well-crafted subject line can significantly improve your open rates, clicks, and response rates, ultimately enhancing your lead generation efforts. Without an enticing subject line, your email outreach won’t get very far.

Let’s delve into the do’s and don’ts of writing compelling cold email subject lines, backed by insights and examples you can use for your own email campaign automation.

The Do’s of Writing Great Cold Email Subject Lines

Do: Write Short Subject Lines

In the age of mobile devices, concise subject lines are crucial. Studies show that 63% of people open their emails on mobile devices, where long subject lines get cut off. Aim for 60 characters or less to ensure your message is fully visible.


  • “[Your product benefit in 3-4 words]”
  • “[Recipient’s Company] <> [Sender’s Company]”
  • “Solution to [problem]”

Do: Personalize It

Personalization is key in cold email automation. Research indicates that personalized subject lines lead to higher open rates. Use the recipient’s name, company, or a recent achievement to make your email stand out. Personalization creates a sense of intimacy and shows that you’ve done your homework, making your prospect more likely to engage.


  • “Really enjoyed your latest post on [publication name]”
  • “Your latest tweet about [topic] made me [reaction]”
  • “Congrats on your recent promotion, [Name]”

Do: Establish Some Kind of Connection

People are more likely to read emails from those they feel connected to. Mention mutual connections, shared experiences, or common affiliations to foster relational interest. This approach makes the recipient feel a sense of familiarity and trust.


  • “[Mutual connection] suggested reaching out to you”
  • “Fellow [university] alum here”
  • “Missed the chance to talk to you at [event]”

Do: Pique Curiosity About Something Relevant

Use your subject line to create suspense and stir curiosity about your email content. Address the recipient’s pain point or tease a valuable resource. This tactic encourages recipients to open the email to learn more about the intriguing subject.


  • “Advice on [prospect’s pain point]”
  • “Interesting case study about [prospect’s industry]”
  • “Noticed a broken link on one of your pages”

Do: Make It Self-Evident

Obvious subject lines often convert well because they clearly communicate the email’s purpose. Avoid overly opaque subjects unless they include a sharp hook that piques interest. Clear and straightforward subject lines save time for busy recipients and help them quickly understand the value of your email.


  • “[Industry] leads for [Recipient’s Company]”
  • “[Recipient’s Company]’s reviews on G2”
  • “Question about [Recipient Company]’s marketing KPIs”

Do: Use Power Words to Grab Prospects’ Attention

Power words like “boost,” “innovative,” and “secret” can elicit strong emotional responses. Be careful not to exaggerate, as this can lead to disappointment. The goal is to evoke interest and excitement without misleading the recipient.


  • “A creative way to engage [prospect’s target audience]”
  • “Our secret to improving ”
  • “New tool that can help automate [process]”

Do: Experiment

There’s no one-size-fits-all formula for writing a winning subject line. Regularly test different subject lines to see what resonates with your audience. Use A/B testing to compare variations and choose the best performer for your email campaign automation. This iterative approach helps you continually improve your email metrics.

The Don’ts of Writing Cold Email Subject Lines

Don’t: Use False Prefixes or Clickbait

Avoid deceptive practices like using “FW” or “RE” in your subject lines, which can trigger spam filters and harm your email deliverability. Clickbait subject lines may get opens but often fail to convert. Be honest and transparent about your email content.

Examples to Avoid:

  • “Re: Potential collaboration”
  • “FW: great news”
  • “Make 10x more money”

Don’t: Write Vague Subject Lines

Vague subject lines can come off as spammy, especially to busy professionals. Provide a clear sneak peek of your email content to avoid ambiguity. Specific and relevant subject lines are more likely to attract attention and interest.

Examples to Avoid:

  • “Check this out”
  • “Quick question”
  • “Website inquiry”

Don’t: Ask for Something Without Offering Anything in Return

Your email should provide value before asking for something in return. Avoid demanding actions from recipients without providing context or benefits. Reciprocity is crucial in cold outreach, so ensure you offer something of value first.

Examples to Avoid:

  • “Let’s hop on the phone”
  • “Request to connect”
  • “I need a post on your website”

Don’t: Use All Caps or a Lot of Exclamation Marks

Subject lines in all caps or with excessive exclamation marks can trigger spam filters and annoy recipients. Aim for a polite and conversational tone instead. Excessive punctuation can make your email appear unprofessional and desperate.

Examples to Avoid:

  • “COMING SOON: This will change your life!”
  • “The perfect solution for [Recipient’s Company]!!!”

Don’t: Write Very Formally or Use Overly Promotional Wording

Keep your subject lines casual and relatable. Avoid jargon and overly formal language that can make your email seem insincere or salesy. Write as if you are speaking to a new friend—polite but conversational.

Examples to Avoid:

  • “Super Sale! Today Only—Act Now!!”
  • “Dearest Madam”
  • “DTC marcomm automation [and any jargon-heavy phrases]”

Advanced Tactics for Writing Cold Email Subject Lines

Connect Subject Line to Preview Text

Take advantage of preview text (the snippet of text that appears in the prospect’s inbox) by treating it as an extension of your subject line. This approach helps when your subject line can’t contain your entire message or when you have a compelling opening line.


  • Subject Line: “Miss in-person networking?”
  • Preview Text: “Look no further—you’re invited to…”

Create a Sense of Urgency

FOMO (fear of missing out) can be a powerful motivator. Creating a sense of urgency can encourage recipients to open your email. However, be cautious not to overdo it, as false urgency can seem clickbaity and lead to distrust.


  • “🎯 How to avoid [problem]”
  • “Reaching out with free tickets—but I’m running low”
  • “[#] days left until [event]”

Include an Emoji

Emojis can add a personal touch and stand out in crowded inboxes. However, their effectiveness can vary based on your audience and brand. Use them sparingly and test their impact on your email metrics.


  • “🚀 Boost your [process] efficiency”


Crafting effective cold email subject lines is crucial for successful email outreach. They should pique interest without misleading recipients. Remember, even the best email content can be overlooked if the subject line doesn’t compel recipients to open it. Keep experimenting, optimizing, and refining your subject lines to see what works best for your audience.

By following these best practices and leveraging email automation tools, you can improve your cold email campaigns, enhance your lead generation efforts, and ultimately drive better results from your email outreach. Always test new ideas, analyze your email metrics, and adjust your strategies based on what works best for your target audience.