How to Cold Email

Subject Line Formula

The subject line is the only variable that determines whether the email gets opened. Two patterns consistently outperform generic subject lines. The first is a personalised reference under 50 characters that shows you read something about the recipient: "Quick question about [company]'s onboarding flow" beats "Exciting partnership opportunity" by a factor of three to five times in open rate because it signals that the email is specifically about them, not a template sent to 5,000 contacts. The second is a specific outcome that's relevant to their role: "How [competitor] reduced CAC by 34%" works because it promises a concrete piece of information rather than a vague benefit.

What doesn't work: subject lines with the word "synergy," "partnership opportunity," "following up on my previous email" as the primary subject line rather than a follow-up, or anything that sounds like it came from a marketing automation platform. Subject lines in all lowercase often perform better than capitalised ones — they look like a message from a real person checking in, not a campaign. A/B test subject lines with any sequencing tool over 50+ emails before drawing conclusions; sample sizes smaller than that produce statistically unreliable results.

Email Body Structure

The entire cold email should consist of three sentences before the ask, then the ask itself, then a signature. Sentence one explains why you're reaching out to this specific person — not "I was browsing LinkedIn and found your profile" but "I noticed that [company] just expanded to enterprise accounts, which means you're probably dealing with [specific onboarding complexity]." Sentence two describes a specific problem you solve or a specific result a similar company achieved. Sentence three is context — why you're qualified to help with that problem, in one sentence.

The call to action should be singular and specific. "Would you be open to a 15-minute call Thursday or Friday this week?" is better than "Would love to chat sometime if you're interested" because it gives the recipient something to respond to. "Let me know if you'd like to learn more" is not an ask — it's passive and places the burden of initiative on the recipient. Brevity signals respect for the recipient's time; emails that are longer than five sentences are read as needing too much of it. The entire email — three sentences, one ask, signature — should take 45 seconds to read.

Follow-Up Sequence

Most cold email replies come from follow-ups, not the initial email. A three-email sequence on a defined schedule converts at two to three times the rate of a single email. Day zero is the initial email. Day three is the first follow-up: add one new piece of information — a relevant case study, a metric that didn't fit in the first email, or a specific question that requires a one-word answer. Day seven is the second follow-up, which should explicitly offer an easy exit: "If this isn't relevant right now, completely understand — just let me know and I won't follow up again." This last line increases responses because it gives people a low-friction way to end the sequence rather than ignoring it, and the responses it generates are either real interest or clean disengagement.

Timing within the day matters less than timing within the week. Tuesday through Thursday mornings, 8–10am in the recipient's timezone, are consistently highest-performing send times. Avoid Monday mornings (inbox recovery from the weekend) and Friday afternoons (pre-weekend mental checkout). Tools like Lemlist allow time-zone-aware sending. If you're running a sequence of 100 or more emails, use Apollo.io's sequencer with its built-in reply detection to automatically pause the sequence when someone responds — continuing to send follow-ups to someone who already replied is a fast way to convert interest into irritation.

Reply Rate Benchmarks

Cold email reply rates vary dramatically with personalisation level. Generic template emails sent to purchased lists average 1–3% reply rate. Emails with light personalisation — a mention of the company name or a recent news item — reach 5–8%. Emails with genuine research — referencing a specific blog post the person wrote, a product decision you saw reflected in their changelog, or a challenge specific to their stage and industry — reach 8–15%. These numbers come from aggregate data across SDR teams at B2B software companies; individual results vary by industry and the quality of the targeting.

The personalisation that drives reply rates is not the kind that takes 30 seconds with a mail merge field. It's the kind that takes three to five minutes per email: reading the person's recent LinkedIn posts, looking at their company's product, understanding the specific challenge someone in their role faces. This time investment limits scale — you can send 20–30 genuinely personalised emails per day, not 500. Tools like Apollo.io and Hunter.io handle the prospecting and email-finding mechanics; Lemlist adds personalised images and video thumbnails. For GDPR compliance, B2B cold email to work addresses under a legitimate business interest is generally permitted in the EU without prior opt-in, provided you include a clear unsubscribe mechanism; consumer email always requires opt-in.

Frequently Asked Questions

How do I find email addresses for cold outreach? Hunter.io finds professional email addresses associated with a domain and provides a confidence score for each. Apollo.io maintains a database of 270+ million professional contacts with email verification. LinkedIn Sales Navigator provides current job titles and company information that helps you identify the right person before finding their email. Verify email addresses before sending — a high bounce rate damages your sender reputation and can get your domain blacklisted by major email providers.

What is the ideal number of cold emails to send per day? For genuine outreach with real personalisation, 20–30 emails per day is the ceiling for one person. For semi-personalised sequences using a sequencer, 50–75 per day is manageable while maintaining quality. Sending more than 100 cold emails per day from a single email address is likely to trigger spam filters at major email providers. If you need scale, use multiple email addresses on different subdomains and warm them up gradually with Lemwarm or Mailwarm before sending high volumes.

How long should I wait before following up with no response? Three to five business days between follow-ups is the standard. Following up after 24 hours reads as impatient. Following up after two weeks suggests you don't prioritise the outreach. For high-value targets — a specific enterprise account or a strategic partner — a longer sequence over three to four weeks with more touchpoints (email, LinkedIn, relevant share) is appropriate. For mid-market outreach at scale, a tight three-email sequence over seven days and then moving on is the most efficient approach.

Is cold calling more effective than cold email? For senior decision-makers (VP and above), cold calling has a higher conversion rate than cold email when done well — a direct conversation is harder to ignore than an email. For technical buyers and individual contributors, cold email is often preferred because it allows them to respond on their schedule. The most effective combination is a cold email first, followed by a call reference to the email: "I sent you an email yesterday about X — wanted to see if you had 30 seconds to hear the short version." This converts the email from a cold touchpoint to a warm-ish opening for the call.

What should I do if someone says "not now" rather than "no"? "Not now" is a future opportunity. Ask "When would be a better time to reconnect?" — a specific month is more actionable than "sometime later." Add them to a quarterly check-in sequence with a genuine piece of value in each touchpoint: a relevant article, a case study from a company in their sector, or a brief update on something you've built that addresses their situation. Buyers who said "not now" and received consistent, respectful follow-up over six months convert at 20–30% within 12 months.