Cold Email Subject Lines: 40 Examples That Get Opened

The best cold email subject lines are specific to the reader, honest about what is inside, and 36 to 50 characters long. The strongest pattern for an agency is the business name plus one thing you noticed, such as "Brightside Dental's booking page on mobile".

Below are 40 lines sorted by what they do, followed by how to write your own.

What makes a cold email subject line work?

Three things, in this order.

It is about them. A subject with the company name or a detail from their website tells the reader the email was written for them. In a study of 12 million outreach emails by Backlinko and Pitchbox, personalized subject lines got 30.5% more replies than generic ones (Backlinko).

It is the right length. The same study found that subject lines of 36 to 50 characters got the best response. Lines of one or two words say too little. Long ones get cut off on a phone.

It is true. The subject has to match the email. That is good manners and it is also the law, as covered below.

A caution on the data. The study dates from 2019 and covers outreach of all kinds, including link requests. Use the direction and test the details on your own list.

40 cold email subject lines by purpose

Square brackets mark what you change. Every example uses a made-up business.

Lines that name something you saw

Use these for your first email. They need a real finding.

1. [Company]'s booking page on mobile
2. A question about [company]'s contact form
3. [Company]'s site took 6 seconds to load
4. Noticed this on [company].com
5. The quote button on [company]'s homepage
6. [Company]'s last blog post is from 2019
7. Your Google listing links to an old page
8. [First name], your menu PDF won't open on iPhone

Filled in. For a made-up dental practice, line 1 becomes "Brightside Dental's booking page on mobile". For a made-up roofer, line 5 becomes "The quote button on Ridgeline Roofing's homepage".

Lines that ask a question

Questions invite an answer. Keep them real.

9. Who looks after [company]'s website?
10. Is the website on your list this year?
11. Can I show you 3 fixes for [company].com?
12. Are you happy with your current site?
13. Does [company] get calls from the website?
14. Open to a second opinion on your site?

Lines that offer something

Say what the reader gets.

15. A 2-minute video review of [company].com
16. 5 quick fixes for [company]'s homepage
17. A free score for [company]'s website
18. Before and after for a [their trade] site
19. A mockup of [company]'s new homepage
20. Notes on [company] vs. 3 local competitors

Lines that use local or trade context

Being nearby, or knowing their trade, is a reason to open.

21. Websites for [trade] in [town]
22. How [town] [trade] sites compare
23. Fellow [town] business with an idea
24. What [trade] customers check before calling
25. [Trade] sites that book more jobs
26. Searching "[service] [town]" this morning

Lines for follow-ups

More on these in our cold email follow-up templates.

27. Re: [your original subject]
28. One more thing on [company]'s site
29. The letter I sent to [street name]
30. Right person for the website?
31. A quick checklist for [company]
32. Closing the loop

Plain lines

Sometimes the least clever line wins, because it reads like a note from a person.

33. [Company] website
34. Quick question, [first name]
35. Idea for [company]
36. [First name], a short note
37. About your homepage
38. Hello from [your town]
39. [Mutual contact] suggested I write
40. Following up on my letter

Use line 39 only when it is true.

How do you adapt a subject line to each business?

Start from the finding, then cut.

1. Look at the site on a phone. Write down the first problem a customer would hit.
2. Write it as a plain phrase. "The booking button is below three screens of text on mobile."
3. Put the company name first. "Brightside Dental, booking button below three screens on mobile."
4. Cut to under 50 characters. "Brightside Dental's booking page on mobile". That is 42.
5. Check it is true and matches the email.

The email then opens with the full detail. Our guide on how to write a cold email covers the rest of the message, and our cold email templates give you a starting point. Subject and first line work as a pair. The subject earns the open and the first line proves the email is worth reading.

Doing this for 20 businesses takes an afternoon. For a list of thousands it is not possible by hand. Twip, the AI inside Leadodo, scores every website in a search across 10 domains, and its findings become the opening line for each business. See how AI Analysis works.

What does the law say about subject lines?

In the United States, the CAN-SPAM Act says a subject line must not be deceptive. It has to reflect what the message contains. The Act covers business-to-business email, and each email that breaks it can carry a penalty of up to $53,088 (FTC).

In practice, three habits keep you safe and also keep you credible.

• No "Re:" or "Fwd:" on a first email.
• No "Your invoice" or "Order confirmation" for a sales email.
• No promise in the subject that the email does not keep.

Rules in other countries are stricter than in the US. This is not legal advice.

Which subject lines should you avoid?

• All capitals and strings of punctuation. They read as spam to people and to filters.
• Fake urgency. "Last chance" from a stranger is not believable.
• Vague flattery. "Love what you're doing" could be sent to anyone.
• The pitch itself. "We build modern websites for dentists" tells the reader it is an ad before they open.
• Tricks with first names alone. "[First name]?" works once. Then it reads as a tactic.

How do you know which line is better?

Test two lines on the same kind of prospect and count replies and ignore opens. Open tracking has become unreliable, because several mail apps load images automatically and report an open that never happened.

Send each line to at least 100 similar businesses before you judge. With fewer, chance decides the winner. And change one thing at a time. If you change the subject and the first line together, you learn nothing about either.

One finding from our own testing is worth keeping in mind. Across 3,570 cold emails, the biggest difference came from who we emailed. Businesses with weak websites replied positively about 3.2 times as often as the rest, with the same email. A better subject line helps. A better list helps more. The numbers are in our write-up.

Questions

What is the best subject line for cold email?

The one that names the reader's business and one specific thing you noticed about it. "Brightside Dental's booking page on mobile" beats any clever line, because only one business could have received it.

How long should a cold email subject line be?

Between 36 and 50 characters, according to a Backlinko and Pitchbox study of 12 million outreach emails. That is about 5 to 8 words, short enough to show in full on most phones.

Should I use the recipient's name in the subject line?

The company name usually works better than the first name. A first name in a subject from a stranger can feel like a mail merge. A company name with a real detail shows you looked.

Do emojis help in cold email subject lines?

For local business owners, usually no. An emoji makes a first email from a stranger look like a promotion. Save them for people who already know you.

Is it okay to use "Re:" in a cold email subject line?

Only on a genuine reply to your own earlier email in the same thread. On a first email it misleads the reader about a conversation that never happened, and US law prohibits deceptive subject lines.

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Next step. See how your Outbound Machine writes a first line from each prospect's own website. Outbound Machine.