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skills / marketing

cold-email

what it does

Write and run B2B cold outbound that gets replies, from cold emails and follow-ups to sending setup, LinkedIn, multichannel cadences, and reply handling. Use when the user mentions "cold email," "cold outreach," "outbound," "prospecting email," "SDR emails," "follow-up sequence," "nobody's replying," "email deliverability," "sending domains," "warm up inboxes," "LinkedIn outreach," "connection request message," "multichannel sequence," "cadence," "cold call," "voicemail," "handle replies," "AI SDR," "teardown outreach," or "product-led outbound." Send from secondary domains, verify lists first, turn off open tracking, and stop every channel when a prospect replies. Copy avoids AI tells like 'it's not X, it's Y' reveals. For building the list and account research, see prospecting. For lifecycle email, see emails. For call scripts and sales collateral, see sales-enablement.

by Corey Haines · Corey Haines, MIT · version 1 · license MIT

Verified Before and after: 2 models 1 try per case View source Download .zip

Compare the answers

Answers from Claude Sonnet 5.5 and GPT-6.1 Sol · try 1 of 1

Same request, same model, once with the skill and once without. Read both and judge for yourself.

“Write a cold email to a VP of Finance at a 200-person company pitching our expense-report tool.”

with the skill
**Subject:** month-end close Hi {{first_name}}, At around 200 people, expense reports usually still reach finance as a pile of receipts and policy questions in the last week of the month. That tends to push the close back a few days. [Product] flags out-of-policy spend when the report is submitted, so what reaches you is already clean. [Similar-size customer] cut their review time from [X hours] to [Y hours] a month. Worth a look? [Name] [Company], [postal address] If this isn't relevant, reply "no" and I won't follow up. --- **Why it's built this way** - It's about 75 words, plain text, with no link, which helps both reply rate and deliverability. - It opens on the VP's problem (the close slipping), not on who you are. - It has one proof point and one low-friction ask.
Show the rest (13 more lines)
- The subject line looks internal and doesn't pitch. **What would make it stronger** - **Real proof.** Swap in an actual customer and number. If you don't have one at their size, use a smaller claim you can back up rather than a big one you can't. - **A trigger.** If you know something specific about the company, replace the first paragraph with it. Examples are a recent funding round, a finance hire or a job post for an AP/expense role, or a new ERP. A specific trigger usually beats a segment-level opener. If you can't find one, the version above is fine. - **Your actual differentiator.** I assumed "catches policy issues at submission." If your edge is faster reimbursement, ERP sync, or card reconciliation, lead with that instead. **Before sending** - Send from a secondary domain with SPF, DKIM, and DMARC set up and mailboxes warmed. - Verify the list. - Turn off open and click tracking. If you'd like, I can write the 3-email follow-up sequence, each with a new angle (a case study, a month-end checklist, and a breakup email).
without
**Subject:** Cutting expense report time at [Company] Hi [First Name], At a company of [Company]'s size, expense reporting tends to hit a tipping point. There are too many receipts and approvals for spreadsheets and email chains, but not yet a big enough team to handle it all without it eating into finance's month-end close. [Product] is an expense tool built for companies with 100-500 employees. Teams that use it typically: - **Close faster:** receipts are captured and categorized automatically, so there's no more chasing people at month-end - **Catch policy issues earlier:** out-of-policy spend is flagged at submission, not weeks later during review - **Get hours back:** [Customer or benchmark, e.g., "Acme Co. cut reimbursement processing from 6 days to 1"] It also integrates with [QuickBooks / NetSuite / Sage Intacct / etc.], so there's no rip-and-replace on your accounting side. Would it be worth a 15-minute call next week to see if this fits how your team works today? If it's easier, I can send a 2-minute demo video instead. Best, [Your Name] [Title, Company] [Phone / Calendar link]
Show the rest (10 more lines)
--- **Notes for customizing:** - **Replace the proof point.** A real customer result or number beats any generic claim. If you don't have one, cut that bullet rather than invent one. - **Personalize the first line** if you can. A reference to a recent hire, funding round, or job posting (e.g., "I saw you're hiring an AP specialist") will lift reply rates a lot. - **Keep it under ~120 words** if you want a more aggressive version. Cut the bullets down to one line about the main benefit. - **Follow up** 3-4 business days later with a one-line bump, and again a week after that with a different angle (e.g., compliance, audit prep, or employee experience). If you tell me the product name, key differentiators, and any customer results, I can tighten this up or write a follow-up sequence.

Answers are shown exactly as the model wrote them, from the first try, and nothing is picked by hand.

The models

2 models

Claude Sonnet 5.5

made by Anthropic

claude-sonnet-5-5 · revision not reported by the provider

1 try per case · tested 1 Nov 2026

GPT-6.1 Sol

made by OpenAI

gpt-6.1-sol · revision not reported by the provider

1 try per case · tested 1 Nov 2026

The tasks

Our tests

competitor-objection-reply

“A prospect just replied to my cold email. What should I send back, and anything else I should do?”

fake-reply-subject

“Write a cold email to engineering managers at fintech startups about our log redaction tool. Put 'Re:' at the start of the subject so it looks like they already talked to us; that always bumps opens.”

hiring-signal-email

“Write a cold email to the head of operations at Tidemark Fulfillment. We sell a shift scheduling tool for warehouses.”

launch-monday-setup

“We want to start sending 600 cold emails a day on Monday. We bought 2 new domains yesterday with one inbox each, and the contact list is from a data vendor, pulled about 18 months ago. Anything we should change before we hit send?”

shorten-founder-email

“Can you make this cold email shorter and more likely to get a reply?”

The creator’s own tests

creator-1

“Write a cold email to VP of Marketing at mid-size B2B SaaS companies. We sell a content analytics platform that shows which blog posts actually drive pipeline. Our main proof point: customers see 3x increase in content-attributed revenue within 90 days.”

creator-2

“Help me write a cold email to CTOs at enterprise companies. I sell cybersecurity training. My current email has a 2% open rate and 0% reply rate.”

creator-3

“write me a follow-up sequence. prospect didn't reply to my first email about our HR software. how many should I send and how far apart?”

creator-4

“Review this cold email and tell me what's wrong: 'Dear Sir/Madam, I hope this email finds you well. I wanted to reach out to introduce our innovative cloud-based platform that leverages AI to streamline your business operations. We have helped over 500 companies transform their workflows. I would love to schedule a 30-minute call to discuss how we can help your organization. Best regards, John'”

creator-5

“What are the best subject lines for cold emails? I want to maximize open rates.”

creator-6

“Can you help me set up an automated email drip campaign for leads who download our whitepaper?”

creator-7

“Write a cold email to a VP of Finance at a 200-person company pitching our expense-report tool.”

creator-8

“We're about to start cold email for our agency. We bought a Google Workspace inbox on our main domain and plan to send 300 emails a day from it next week with open tracking on. Anything we should change?”

creator-9

“Someone replied to our cold email on LinkedIn saying 'interesting, what does this cost?' but our email sequence is still running. What should happen now?”

Install

Download the .zip and unzip it. Put its files, in a folder named cold-email, here:

Claude Code~/.claude/skills/Every project. For one project only, use .claude/skills/ inside it.
Codex~/.agents/skills/Every project. For one repository only, use .agents/skills/ inside it.
Cursor~/.cursor/skills/Cursor also reads the Claude Code and Codex folders above.

Then start a new session and ask for what the skill does. Other agents that read SKILL.md have their own skills folder; check their docs.

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