What is cold email? The meaning, the rules and how it works

Cold email is a one-to-one business email sent to someone who has never heard from you, written around a specific reason to contact them, with one ask: a reply. It is the email version of a cold call. Reachly runs cold email for B2B companies, and in our client campaigns each email is 60 to 80 words, carries no links, and goes out as a two-email sequence sent five to six days apart. This page covers what the term means, how a campaign works from list to booked meeting, the laws and inbox rules that apply, and what it costs to run.

Key Findings

• A cold email goes to one named person you have no prior relationship with, gives a reason tied to their role or company, and asks for a reply.
• Targeting and honesty separate it from spam: one recipient, a real sender with a real address, a relevant reason, and an easy way to opt out.
• Cold email is legal in the US under the CAN-SPAM Act, which covers business-to-business email too: honest headers and subject lines, a postal address, and opt-outs honored within 10 business days. Canada's CASL is stricter and needs consent, express or implied.
• Gmail asks every sender to keep spam complaints under 0.3%. Gmail and Outlook both require SPF, DKIM and DMARC from domains sending more than 5,000 messages a day.
• Reachly's working rules: 60 to 80 words, no links, two emails five to six days apart, bounce rate under 2%, and first meetings 2 to 6 weeks after launch. The full method is on our agency service page.
• A 30,000-email month for one client runs on 72 domains and 180 mailboxes. Most of the cost sits in infrastructure and data, and the sending software is the cheapest line.
• Primal's campaigns averaged an 8% positive reply rate and produced 85+ sales qualified leads in six months.
• In Reachly's Smartlead data from 5 October 2026, the three client sequences with the highest share of interested replies, 34% to 39%, open on the reader, run 39 to 107 words and make one small ask.

What does cold email mean?

The word cold describes the relationship, not the tone. The person on the other end is not expecting you: they have not opted in, bought from you, or spoken to you before. The term comes from cold calling, and it works the same way. Once someone replies, the thread is warm, and every message after that is a conversation.

A message counts as a cold email when four things are true:

• No prior relationship. The recipient never subscribed, never bought, and never met you.
• One recipient. It is written to one named person in a specific role, even when software does the sending.
• A reason. Something about their company makes the message relevant now. Reachly calls that a buying signal: a new hire, a funding round, a jump in headcount.
• One ask. The goal of the first email is a reply. The meeting comes after.

Who sends cold email

Sales teams send most of it, to open conversations with accounts that fit their ideal customer profile. Founders use it to reach investors and first customers, recruiters use it to reach candidates, and job seekers use it to reach hiring managers directly. PR teams and SEO teams use it for press and link requests.

This page is written for the B2B sales use, because that is where the volume, the laws and the inbox rules bite hardest. The definition is the same when you write to a hiring manager, and the FAQ below covers the differences. For the sales version end to end, our best practices guide goes deeper on each step.

What a cold email looks like

Here is an example written for this page to the same rules Reachly uses in client campaigns. The trigger comes first, the body stays under 80 words, there are no links, and it closes on one question that is easy to answer.

Subject: your new Head of Growth

Hi Dana,

I see you just hired a Head of Growth. A new growth lead
usually inherits a pipeline target before the channels to
hit it are in place.

We build outbound for B2B teams in that spot: the lists, the
sending domains and the replies, so the new hire has
meetings to work with in their first two months.

Worth a short conversation, or is outbound already covered?

Thibault

Each line has one job. The first line proves the email was written to this person and names why now. The second line names a problem the reader probably has because of that trigger. The third says what we do in terms of their situation. The last line asks a question they can answer in one word, and it gives them a polite way to say no.

For 30 more, sorted by situation, see our cold email templates. The rules behind the length are in email length, and the subject line rules are in the subject lines guide.

How is cold email different from spam, email marketing and warm email?

The four get confused because they share an inbox. They differ on who the recipient is, why they are getting the message, and what the sender wants back.

The line that matters most in practice is the one between cold email and spam, and inbox providers draw it with complaint data. A message that enough recipients report gets treated as spam, however good its targeting was. That is why the infrastructure in the next section exists, and why our guide to avoiding the spam folder starts with the list rather than the copy.

How does cold email work, from list to booked meeting?

A single email is easy to write. A campaign is a system with six moving parts, and most of the work happens before the first message goes out. This is the order Reachly runs it in, with the timing from our client engagements.

Build the list around a signal

Every list starts with accounts, not contacts. We define the ideal customer profile, then filter for a live trigger, such as a new marketing hire, a funding round or falling organic traffic. The trigger becomes the first line of the email, so one list carries one signal. Our B2B buying signals guide ranks the signals that convert, and the signal-based outbound playbook shows how to turn each one into a campaign.

Verify every address

Every contact gets verified before it is loaded. We hold bounce rate under 2% and treat anything above 5% as a level that risks provider blocks, because bounces are one of the first things a mailbox provider reads. The process and the tools are in email verification.

Send from dedicated, authenticated domains

Outreach never goes out from the company's main domain. Reachly buys secondary domains, sets up SPF, DKIM and DMARC, and warms them for 4 weeks before real volume, so a bad week can never reach the domain your invoices and customer email depend on. The setup is in SPF, DKIM and DMARC setup, the timeline in how long to warm up a domain, and the rotation rules in inbox rotation.

Write one short email per signal

The email names the trigger first, stays between 60 and 80 words, carries no links and asks one question. Personalization means matching the message to the signal, which is covered in cold email personalization. The ask itself is the offer, and a weak offer sinks good copy; see offer examples.

Follow up once, in the same thread

Our client sequences run two emails, five to six days apart, while LinkedIn and the phone carry the other touches. Timing, wording and when to stop are in our cold email follow up guide.

Turn replies into meetings, then measure

A reply is the start of the sale, so every one gets triaged within the day: interested, not now, wrong person, or opt-out. Qualified replies become meetings, which is where the first ones land, 2 to 6 weeks after launch. Judge the campaign on positive reply rate rather than opens, and compare yours with the response rate benchmarks.

Is cold email legal?

Yes, in the US, the UK and most of the EU, as long as the email follows the rules of the country the recipient is in. The US law is the loosest: the FTC CAN-SPAM guide requires no prior consent, but it does apply to business email, stating that the law "makes no exception for business-to-business email." Canada is the strictest of the four markets below.

The US rules in full come to eight requirements, and the ones sales emails most often break are the postal address and a real opt-out. A sales email with neither is out of compliance even if it went to one person. This table is a summary to help you scope a campaign. It is not legal advice, so check with counsel before you email into a new country.

What do Gmail and Outlook require from cold email senders?

Since February 1, 2024, Google requires every sender to Gmail accounts to set up SPF or DKIM, have valid forward and reverse DNS, use TLS, and keep the spam rate shown in Postmaster Tools below 0.3%. Google recommends staying under 0.10%. Domains sending more than 5,000 messages a day to Gmail also need SPF and DKIM together, a DMARC record aligned with the From address, and one-click unsubscribe on marketing mail.

Outlook set the same bar for domains sending more than 5,000 emails a day: SPF and DKIM must pass, and DMARC must be at least p=none and aligned with one of them. Enforcement started on May 5, 2025, and non-compliant mail is junked or rejected with a 550 5.7.515 error.

The complaint rate is the number that ends campaigns. You can read yours for free in Google Postmaster Tools, and the wider fixes are in our deliverability playbook.

Does cold email still work in 2026?

Yes, when the list is built on a real signal and the infrastructure holds up. For Primal, a marketing services company in Thailand, Reachly ran one evergreen campaign into CMOs and CEOs plus signal-based campaigns on hiring, funding and falling search traffic. The campaigns averaged an 8% positive reply rate, produced 85+ sales qualified leads and 6 new deals in six months, cut cost per acquisition by 35%, and returned 4.57x on the engagement, breaking even at month three.

For The Great Room, a premium co-working operator in Singapore and Australia, Reachly's outbound meetings dropped off at about 30%, against about 50% from paid channels, and contributed to a contract worth about $250K. Email worked there alongside LinkedIn, which is how Reachly runs every campaign: cold email, LinkedIn and cold calling together.

What stopped working is the high-volume, low-relevance version. Gmail's 0.3% ceiling means a campaign that annoys one recipient in 300 is already in trouble. If you are weighing email against the phone, cold email vs cold call compares the two.

What do cold emails that get interested replies look like?

The three sequences below are live client campaigns from Reachly's Smartlead workspace, pulled on 5 October 2026. Among every client campaign that has sent at least 2,000 emails, they have the highest share of interested replies, meaning interested replies as a share of all replies. Each is shown the way the prospect read it, with the merge tags highlighted.

"Interested" is Smartlead's own category flag, so read it as an upper bound on real positive replies. Reply counts include out-of-office messages, which makes the share slightly understated. Client and sender names are removed; the copy, the merge tags and the send timing are as sent.

Sequence 1: the free valuation

Why it works. The subject is two lowercase words, the way a person writes a note to someone they know. The first line is a yes or no question about something the reader owns, so answering costs nothing.

The second line gives the reason for asking, and it is a problem most collectors have without noticing it: the prices they can look up lag the private market by years.

The ask is a free valuation. "Send me what you've got and I'll tell you where it sits" is useful to the collector even if they never sell, which is why a reply here is already a sign of interest. Of its 66 replies, 26 were interested, the highest share in the workspace.

Credibility goes in the PS, where it backs the offer without slowing the read. The second email lands a day later in the same thread with a new angle, the market and its missing liquidity, and a smaller ask.

Sequence 2: the building they work in

Why it works. The signal is proximity. The sender has been in the prospect's building, and the subject line names it, so the CEO sees their own address before anything else. That takes a custom field, {{building_name}}, filled for every lead, which is list work most senders skip.

{{sl_day_of_week}} is Smartlead's day-of-week tag, so the greeting always matches the day the email lands. It is a small detail that reads as typed by hand.

The middle names the CEO's real cost, the time it takes to vet fit-out vendors, then gives one line of proof and one line of offer. The ask is a coffee with "no pitch" and local examples, a small yes for a busy reader.

The follow-up waits six days and brings a new reason to care, the office as part of hiring, then offers a way out that still helps: loop in {{colleague_name}}.

Sequence 3: one outcome, one deadline

Why it works. The whole pitch is one sentence: a specific outcome, in a category the reader belongs to, with a deadline. {{company_type}} makes the promise read as written for their kind of business, and the subject puts their company name next to the thing they are worried about.

Variant A asks for permission to send a video, an easier yes than a meeting. Variant B asks for a 15-minute call. The two ran as a split and the figures above combine them, so this data cannot say which ask won.

The follow-up is one sentence. It repeats the offer and adds the referral route, so a reader who is the wrong person can still reply usefully.

A two-sentence email kept a third of its replies interested, which says the list and the promise were matched to each other.

What the three have in common

• The first email runs 39 to 107 words, sign-off and PS included, and the shortest is two sentences.
• Each one opens on the reader: their cards, their building, their company's name in ChatGPT. The sender comes in later, in a single line of proof.
• Each email makes one ask, and the ask is small: send what you have, a coffee, a short video.
• Every follow-up replies in the same thread and brings a new angle. None of them asks whether the reader saw the last email.
• Two of the three give the reader a referral route in the second email, so the wrong person can still send a useful reply.
• None carries a link or an attachment, and all three go out under a founder's name.

The same rules sit behind the example email earlier on this page. Reachly writes every client sequence to them, and the cold email follow-up guide covers the second email in more depth.

What does it cost to run cold email at volume?

Software is the cheap part. This is the stack Reachly runs for one client sending 30,000 emails a month, as published on our outbound lead generation page.

Two ratios in that table explain how volume works without burning domains. It comes to 2.5 mailboxes per domain, and 30,000 emails spread over 180 mailboxes is about 167 per mailbox a month, or roughly 8 a working day. On top of that, about 30% of the infrastructure is held in reserve, so a tired mailbox can come out of rotation without pausing the campaign. Volume comes from spreading the sends thin across many mailboxes, so each one keeps a low daily count.

Reachly runs that whole stack, plus the copy and reply handling, on a flat monthly retainer from $3,500. To model what a campaign would return for your deal size, use the ROI calculator, or see how an agency engagement works on our agency page.

Which cold email guide should you read next?

Every guide on the Reachly blog covers one part of the system above. Start with the stage you are stuck on.

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FAQ

What is the 30/30/50 rule for cold emails?

There is no single version of it. Searching the phrase turns up at least three different rules: a content split of 30% personalization, 30% value and 50% call to action; an effort split of 30% list, 30% copy and 50% follow-up; and a set of targets of 30% opens, 30% replies and 50% of replies converting. None of them traces back to a study, so treat the phrase as a reminder that follow-up and targeting carry as much weight as the first email, and nothing more.

What is the 3 email rule?

It usually means stopping after three emails to someone who has not answered. There is no official version, and the right number depends on how many other channels you run. Reachly's client sequences stop at two emails, because LinkedIn and the phone carry the later touches, and a third email to the same silent inbox adds more complaint risk than replies.

Does cold emailing work for getting a job?

Yes, and it follows the same shape as a sales email: one person, a reason, one small ask. Write to the hiring manager or a future teammate instead of a careers inbox, name the role or the project that made you write, and ask for a short call or a pointer to the right person. CAN-SPAM covers commercial messages that advertise a product or service, so a personal job inquiry generally falls outside it, but honesty about who you are still decides whether you get a reply.

Should I attach a CV to a cold email?

Leave it out of the first email. An attachment from a stranger is one more thing for a filter to scan and a reason for a careful reader not to open the message. Put the two or three facts that matter in the body and offer to send the CV if they want it. Reachly's sales emails carry no links for the same reason.

How many cold emails should I send in a day?

Count per mailbox, not per company. A new domain should send nothing beyond warm-up traffic for its first four weeks, and after that the safe number per mailbox stays low. In the 30,000-email month above, each of 180 mailboxes averages about 8 sends a working day. If you need more, add mailboxes and domains instead of pushing each one harder; how to send 5,000 cold emails a day shows the build.

What is the 12 second rule for emails?

It is the idea that a reader decides within about 12 seconds whether to reply, archive or delete an email. No single study is behind the number, but measured attention points the same way and keeps shrinking: Litmus found people looked at an email for 13.4 seconds on average in 2018 and 9 seconds in 2022, and 30% of emails got under two seconds (Litmus data, via MarketingProfs). For cold email that window holds the sender name, the subject and the first sentence, so the reason for writing has to sit in that first sentence.

What is the best day to send cold emails?

The day matters less than the hour. Smartlead's platform data, published on 28 September 2026, puts weekday reply rates in a narrow band: Wednesday 0.91%, Tuesday 0.90%, Thursday 0.89%, Monday 0.88% and Friday 0.87%, with Saturday lowest at 0.82%. The hour moved results far more: an email sent at 7am in the recipient's time zone earned a 1.34% reply rate against 0.82% at 4pm (Smartlead). Schedule Tuesday to Thursday mornings in the prospect's own time zone, which matters most when one campaign spans the US and APAC.

How do I write cold emails?

Write the reason first and the pitch last. Start with the one sentence that says why this person, now: a hire, a building, a gap you can see. Add one line on the problem that reason creates, one line of proof, and one question that takes seconds to answer. Then cut every sentence about you that the reader does not need to say yes. Write the follow-up before you send the first email, so it carries a new angle and a referral route instead of a reminder.