What is cold email? Meaning, legality and how to write one

Cold email is a personal email sent to someone you have no prior relationship with, usually to start a business conversation such as a sale, a partnership or a hire. It is "cold" because the reader does not know you yet, and it works when you have a specific, relevant reason to write to that one person.

This guide is for agency owners, freelancers and founders who want to win clients by email without becoming a spammer. It covers what cold email means, when it is legal in the US, UK and EU, whether it still works, how to write one and the deliverability basics.

What is cold email?

Cold email is an unsolicited email to a specific person you have not met, written to start a relevant business conversation. The opposite is warm email, where the reader already knows you, was introduced to you or asked to hear from you.

A short example: a freelance web designer notices that a local physiotherapy clinic's website has no online booking. She emails the clinic owner, names the problem, links one similar site she built and asks if a mock-up would be useful. That is a cold email. The owner has never heard of her, but the email is about the owner's business, not a generic pitch.

Common uses:

• Winning clients: agencies, freelancers and B2B companies contacting likely buyers.
• Partnerships: reaching a company whose customers overlap with yours.
• Hiring and jobs: recruiters contacting candidates, or candidates contacting hiring managers.
• PR and links: pitching a story or a resource to a journalist or editor.

What makes it cold is the lack of a relationship, not the tone. A cold email can be warm in style, and should be.

What is the difference between cold email and spam?

Cold email is targeted, personal and honest, sent to people whose job makes the message relevant. Spam is bulk, untargeted or deceptive, sent with no thought about whether the reader cares.

The line between them is not only ethics. It decides whether your emails land at all. Mailbox providers measure how many people mark your messages as spam, and they act on it, as covered in the deliverability section below.

Is cold email legal?

Yes, cold email to business contacts is legal in the US, the UK and the EU, as long as you follow each place's rules on identity, opt-outs and data. The rules differ, so check where your recipient is, not where you are. This is general information, not legal advice.

Is cold email legal in the US?

Yes. The US CAN-SPAM Act does not require consent, and the FTC says "the law makes no exception for business-to-business email". So every commercial email must follow its rules:

• Don't use false or misleading header information.
• Don't use deceptive subject lines.
• Identify the message as an ad.
• Tell recipients where you're located, with a valid postal address.
• Tell recipients how to opt out, and honour opt-outs within 10 business days.

The FTC says each email in violation can bring penalties of up to $53,088. That alone is a good reason to put a real address and opt-out line in every email.

Is cold email legal in the UK?

Yes, to businesses. The UK's PECR rules on email marketing, explained in the ICO's guidance, say "You can email or text any corporate body", such as a limited company or LLP. You must not hide your identity, and you must give a valid address to opt out.

Two catches. First, "sole traders and some partnerships are treated as individuals", so you need their consent, or an existing customer relationship with an opt-out offered. Second, the ICO's business-to-business marketing guidance says "the UK GDPR still applies to B2B marketing if you are processing personal data", and a named address like jane@company.co.uk is personal data. It says legitimate interests will often be the right lawful basis, and that the right to object to direct marketing "is absolute". The ICO also notes its PECR guidance is under review following the Data (Use and Access) Act, so check the current version.

Is cold email legal under GDPR in the EU?

Usually yes, for relevant B2B messages, on the basis of legitimate interest. GDPR Recital 47 says "the processing of personal data for direct marketing purposes may be regarded as carried out for a legitimate interest". Article 21 gives people the right to object to direct marketing "at any time", after which their data "shall no longer be processed for such purposes".

In practice that means:

1. Write down why your offer is relevant to this person's role (your legitimate interest).
2. Only collect what you need: name, work email, company, role.
3. Tell people where you got their details if they ask, and in your privacy notice.
4. Keep a suppression list so people who object are never emailed again.

EU countries also have their own national rules on email marketing, and some are stricter than others for business addresses. Before emailing into a new country, check its data protection regulator's guidance.

Do cold emails still work?

Yes, cold emails still work, but the average result is modest and the spread between good and bad senders is huge. Hunter's State of Cold Email 2026, based on 31 million emails sent in 2025, puts the average reply rate at 4.5% and 3% for sales emails.

The same report shows what separates the winners:

• Smaller lists: sequences to 21 to 50 people got 6.2% replies, against 2.4% for 500 or more.
• Real personalisation: two custom attributes in the body got 5.6% against 3.6% for none.
• Your own domain: custom domains got 5.2% against 2.5% for free email addresses.
• Follow-ups: three messages got 6.8% against 3.3% for one.

Readers are not against it either: Hunter found 58% of decision makers receive something useful by cold email at least monthly. But 65% say cold emails feel too pushy or sales-focused, and 61% cite irrelevance. The channel works; most emails in it are poor.

What does 3% mean in practice? Say you run a two-person SEO agency and send 40 emails a day, four days a week. That is 160 emails a week. At 3%, about 5 people reply; at 6%, about 10. If a third of replies are interested and one in four of those becomes a client, a 6% reply rate gives you roughly three new clients a month. For more numbers, see our cold email reply rate benchmarks.

How do you write a cold email?

Write a cold email in four parts: a specific reason for writing, the reader's likely problem, one line on how you help, and one small question. Keep it under 100 words and plain text, with your real signature and an opt-out line.

Here is the anatomy:

1. Subject line. Two to six plain words about them: "your Leeds clinic", "{company}'s checkout". Hunter found 5 to 6 words was the sweet spot for reply rates.
2. Opening line: the reason. A fact they can check: a job post, a launch, a new location, a problem on their site.
3. The problem. What that fact usually costs them, in one sentence.
4. Proof. One line: a relevant result you can show, a portfolio link or what you noticed.
5. The ask. One small question, such as "want the notes?" rather than "can we book an hour?".
6. Signature and opt-out. Name, business, postal address and "reply 'no' and I won't email again".

Put together:

If no reply comes, send two or three short follow-ups that each add something new, then stop. Our guide to the follow-up email after no response has timing and templates, and our cold email templates cover 12 common situations.

What are the cold email deliverability basics?

Deliverability means your email reaches the inbox instead of spam. The basics are an authenticated domain, a low spam complaint rate, modest daily volume per mailbox and emails people actually want.

Google's email sender guidelines ask every sender to set up SPF or DKIM, keep spam rates "below 0.10%" and "avoid ever reaching a spam rate of 0.30% or higher". Senders of more than 5,000 messages a day to Gmail accounts must also set up DMARC and one-click unsubscribe. Our guide to email sender requirements in 2026 explains each record.

A practical setup for a small agency:

Remember the 0.3% figure: for every 1,000 emails, three spam reports puts you at Google's limit. That is why targeting matters more than volume.

What are the best cold email tips?

The best cold email tips are about relevance, not tricks. Pick fewer, better-fit people, research one real fact about each, and make it easy to say yes or no.

• Write to one or two people per company. Hunter found 5.1% replies against 3.5% for three or more.
• Time it with a signal. Hiring, funding or a new location gives you a natural reason to write.
• Lead with them, not you. Cut sentences that start with "We are" or "I am".
• Ask a small question. Offer notes, a video or a mock-up before asking for a call.
• Send plain text. No images, no heavy formatting, at most one link.
• Edit by hand. Hunter found manually edited emails got 5.2% against 4.4% for fully automated ones.
• Stop after three or four emails. Then move on.

Where Outbind fits

You can do everything above by hand, and for 10 to 20 emails a day you probably should, at least at first. It teaches you what your buyers care about.

The hard part is doing it every day: finding people who fit, spotting a reason to write, researching each one and following up. Outbind does that work. It maps your market, watches for signals like hiring and funding, writes emails that cite real sources and sends plain-text emails from your own inbox, with a slow start for new mailboxes, and stops when someone replies. Your data is stored in the EU. If you are a freelancer, see how it works for freelancers, or compare plans on the pricing page.

FAQ

What does cold email mean?

Cold email means emailing someone you have no existing relationship with, usually to start a business conversation. "Cold" refers to the lack of prior contact, not to the tone of the message.

Is cold emailing illegal?

No. Cold emailing businesses is legal in the US, UK and EU if you follow the rules: honest identity and subject lines, a postal address in the US, a working opt-out and a lawful basis for using personal data under GDPR. In the UK, sole traders and some partnerships are treated as individuals and usually need consent.

Is cold email the same as spam?

No. Cold email is a relevant, one-to-one message from an identified sender with an easy opt-out. Spam is bulk, irrelevant or deceptive, and is what spam filters and laws target.

What is a good cold email reply rate?

Hunter's 2026 report puts the average at 4.5% across all uses and 3% for sales emails. A focused campaign to a small, well-researched list can reach 5 to 10%.

How many cold emails should I send a day?

Start with 20 to 50 per mailbox per day and grow slowly. Hunter found 20 to 49 emails per day per account had a 5.7% reply rate, above its 4.5% average.

Do I need consent to send a cold email?

In the US, no. In the UK, not for limited companies and other corporate bodies, but yes for sole traders and some partnerships. In the EU, B2B emails usually rely on legitimate interest, but check national rules in each country.

Sources

• FTC: CAN-SPAM Act compliance guide for business
• ICO: Electronic mail marketing (PECR)
• ICO: Business-to-business marketing
• GDPR Recital 47
• GDPR Article 21: Right to object
• Hunter: The State of Cold Email 2026
• Google: Email sender guidelines