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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:** expense reporting Hi [First name], With 200 people, missing receipts and late expense reports can mean extra chasing at month-end. [Tool] helps employees submit expenses and finance teams review them with less back-and-forth, so your team can focus on closing the books. Worth a look? [Your name] [Company] | [Postal address] If this isn’t relevant, reply “no” and I won’t follow up.

without

**Subject:** Less back-and-forth on expense reports Hi [First Name], At a 200-person company, expense reports can create plenty of work for Finance—chasing receipts, checking policy compliance, and following up on approvals. [Product] helps employees submit expenses and gives Finance a clearer way to review and manage them, with less back-and-forth. Is streamlining expense reporting a priority for your team? If so, would you be open to a 15-minute walkthrough next week? Best, [Your Name] [Company]

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.

Coming after launch: get skills from inside your agent, no download needed.