Cold email skills for Claude and other AI assistants
Each skill is a SKILL.md file with the checks we run when we set up and debug cold email. Install it in Claude or Claude Code, or paste it into ChatGPT, Gemini, Grok or Cursor as instructions.
Copy skills
Write and check the emails before they go out.
- Cold email copy fatigue and rotationGive the assistant your live templates and their daily step-1 numbers, and it groups them into structural families, flags the tired ones against their own peak and returns a rotation plan with canary slices.SKILL.md · view and download
- Cold email copy reviewerPaste a cold email and the assistant checks it against length, structure, call-to-action and wording rules, lists each violation with the fragment, and returns a rewrite that keeps your offer.SKILL.md · view and download
- Cold email follow-up sequence plannerTell the assistant your first email and your sequencer, and it returns a five-step plan (the first email plus 4 follow-ups) with the day of each step, the delay values to enter, the text of each follow-up and the stop rules to switch on.SKILL.md · view and download
- Cold email link checkerPaste your cold email and signature and the assistant lists every URL, bare domain, image and tracking element, then rewrites the copy so the first email carries none of them.SKILL.md · view and download
- Merge variable render checkPaste your template and your lead file header with sample rows, and the assistant maps each variable to a column, flags casing mismatches and bad values, and renders five real leads before you activate.SKILL.md · view and download
- Cold email opener writerGive the assistant your offer, one concrete number and who you write to, and it writes three first-email variants that ask whether the recipient is a fit.SKILL.md · view and download
- Cold email spintax linterPaste a subject line or email with spintax and the assistant finds every option that will break at send time, explains why, and returns a fixed template with sample renders.SKILL.md · view and download
- Cold email subject line spintax generatorDescribe the email and your merge fields, and the assistant writes subject line families as spintax, counts the renders per family and shows samples with filled and empty fields.SKILL.md · view and download
Deliverability skills
Find out where your emails land and why.
- Email blacklist check for IPs and domainsThe assistant queries the DNS blocklists that matter for email, reads each return code, separates real listings from refused queries, and tells you which listings to fix first.SKILL.md · view and download
- Bounce triage for cold emailPaste your bounce messages and the assistant sorts them into list problems and sender problems, then tells you which addresses to remove and which mailboxes to stop.SKILL.md · view and download
- Burned sending domain detectorGive the assistant per-domain sending stats and it compares each domain with its own history, rules out list and copy changes, and returns keep, rest or retire with the evidence.SKILL.md · view and download
- Spam complaint rate guard for cold emailMost sequencers never show your spam complaint rate, so the assistant checks the settings and habits that cause complaints and returns a pass/fail checklist with fixes.SKILL.md · view and download
- SPF, DKIM and DMARC audit for sending domainsGive the assistant your sending domains and it reads SPF, DKIM, DMARC and MX the way a receiving server does, then returns a pass/fail table per domain with the exact records to publish.SKILL.md · view and download
- Inbox placement test readerShare your seed test results and the assistant reads them per provider, against a neutral control email, and tells you whether the problem is your sending setup, your copy, or too little data.SKILL.md · view and download
- Inbox placement test plannerTell the assistant what you want to learn from placement tests and it returns a test plan with a control, a copy by domain matrix, a schedule within safe limits and a decision rule.SKILL.md · view and download
- Warmup metrics readerA high warmup score measures a cooperative network. Cold inbox placement needs its own test. Share your warmup stats and the assistant tells you which mailboxes are ready, which to investigate and what to test.SKILL.md · view and download
Infrastructure skills
Plan mailboxes, domains and volume.
- Cold email capacity plannerGive the assistant a monthly or daily volume and it returns how many mailboxes and domains you need, how many spares to keep warming, when you reach full volume and what it costs.SKILL.md · view and download
- Cold email sending domain plannerCold email should never go out from your main domain. The assistant works out how many secondary domains you need, proposes names that pass a naming checklist and lays out setup and rotation.SKILL.md · view and download
Operations skills
Clean lists, sort replies, read results.
- Cold email campaign metrics readerShare campaign or A/B numbers and the assistant checks the measurement first, then gives a verdict with a confidence level: winner, no difference yet, or invalid comparison.SKILL.md · view and download
- Cold email lead list cleanerShare a lead CSV and the assistant returns a kept file, a dropped file with a reason for every removed row and a report, so only clean rows with usable merge fields reach your sequencer.SKILL.md · view and download
- Cold email reply classifierPaste replies or an inbox export and the assistant labels each one, extracts follow-up dates and referred contacts, recommends the next action and reports opportunities per 1,000 leads.SKILL.md · view and download
Install a skill in your assistant
The same SKILL.md works everywhere. Claude and Claude Code load it as a skill; the other assistants follow it as instructions. Replace <skill-name> with the skill's name; each skill page has its own commands ready to copy.
Claude Code
- Run the command below to save the skill to your personal skills folder, available in every project; for one project only, use .claude/skills in the project instead
- Start a new Claude Code session; Claude uses the skill when your request matches its description, or when you name it
Terminal
mkdir -p ~/.claude/skills/<skill-name>
curl -fsSL https://outreach2day.com/skills/<skill-name>/SKILL.md -o ~/.claude/skills/<skill-name>/SKILL.mdClaude (web and desktop)
- Download the ZIP file
- In Claude, open Settings, find Skills under Capabilities and upload the ZIP; skills need code execution turned on for your account
- Ask for the task in any chat; Claude loads the skill when the request matches
ChatGPT
- Download SKILL.md
- Paste its text into a Project's instructions or a custom GPT's instructions; for a single chat, attach the file and write: follow the instructions in this file
Gemini
- Download SKILL.md
- Create a Gem and paste the file's text into its instructions, or attach the file to a chat and ask Gemini to follow it
Grok
- Download SKILL.md
- Paste its text into a Project's instructions, or attach the file to a chat and ask Grok to follow it
Cursor and other coding agents
- Save the file as a project rule with the command below; Cursor reads the description to decide when to apply it
- Agents that read AGENTS.md (Codex and others): paste the text into AGENTS.md or reference the file from it
Terminal, in your project
mkdir -p .cursor/rules
curl -fsSL https://outreach2day.com/skills/<skill-name>/SKILL.md -o .cursor/rules/<skill-name>.mdcIn your browser
Free tools that run in your browser
Some of the same checks as standalone web pages.
- Cold email capacity calculatorEnter how many cold emails you want to send a month and get the mailboxes, domains, monthly cost and warmup timeline you need. Free, runs in your browser.
- Cold email cost calculatorEnter cold emails a day or new leads a month and get the mailboxes, domains, warmup time and monthly cost on Outreach2day and six common stacks, with the formula and sources.
- SPF, DKIM and DMARC checkerCheck a domain's SPF, DKIM, DMARC and MX records in your browser: lookup count, policy, key length and what to fix. Free, no sign-up, nothing stored.
- Domain health checkerFree domain health check for email: blacklist lookups for the domain and its mail IPs, SPF, DKIM, DMARC, MX and domain age, with what to fix. Runs in your browser.
- Spintax validatorPaste spintax in {{RANDOM|a|b}} or {a|b} format. See every error that breaks at send time, sample renders with filled and empty fields, and the render count.
- Cold email copy checkerCheck a cold email for links, bare domains, images, spam-trigger phrases, fake Re: subjects and length before you send. Free, runs in your browser.
- Email blacklist checkerFree email blacklist check for a domain or IP: 13 spam blocklists, what each one means and how to get delisted, with Spamhaus linked to check by hand. Runs in your browser.
- Domain reputation checkerFree domain reputation check for email: 13 blocklists, SPF, DKIM, DMARC, MX and domain age in one report, and where Gmail and Microsoft show the rest. Runs in your browser.
- SPF checkerCheck an SPF record: every include expanded as a tree, the DNS lookup count against the limit of 10, void lookups, permerror causes and the corrected record to copy. Free.
- DMARC checkerCheck a DMARC record: the policy and where it sits on the none, quarantine, reject path, every tag in plain words, report addresses, the Gmail and Yahoo rule and the record to copy.
- DKIM checkerCheck DKIM for a domain: enter a selector or let the checker try the ones Google, Microsoft, SendGrid, Mailchimp and others document. Key length, provider, tags and the fix. Free.
- MX lookupLook up a domain's MX records: priorities, the mail provider behind each host, IPv4 and IPv6 addresses, and errors such as null MX, missing hosts and mixed providers. Free.
- SPF record generatorFree SPF record generator: pick Google Workspace, Microsoft 365, SendGrid, Mailgun and more, merge with your current record, count DNS lookups and copy the TXT record.
- DMARC record generatorFree DMARC record generator: pick the rollout stage, report addresses, subdomain policy and alignment, get the TXT record for _dmarc and the next step from none to reject.
- SPF flattening toolFree SPF flattening tool: count every DNS lookup in your SPF record, merge multiple SPF records and replace the heaviest includes with their IPs to get under 10.
- Email header analyzerPaste email headers to see SPF, DKIM and DMARC results with alignment, every hop and delay, one-click unsubscribe and the spam verdict, with fixes. Runs in your browser.
- Email list cleanerDrop an Apollo, Clay or any lead CSV: remove duplicates, invalid, role and free-mail addresses, see contacts per company, download the clean file and get the mailboxes to send it.
Questions
What is a skill for Claude?
A skill is a folder with a SKILL.md file: a short description of when to use it and the instructions to follow. Claude and Claude Code read the description and load the instructions when a request matches, so you do not paste the same prompt every time.
Do these skills work in ChatGPT, Gemini, Grok or Cursor?
Yes, as instructions. Paste the SKILL.md text into a ChatGPT Project or custom GPT, a Gemini Gem, a Grok Project or a Cursor rule. The file is plain Markdown and asks for nothing that only Claude can do.
Are the skills free?
Yes. Download, change and share them. They are the checks we use on our own and our customers' cold email.
Do the skills connect to my sending tool or mailboxes?
No. They work on what you paste or attach: copy, DNS records, bounce messages, CSV exports. Nothing is sent anywhere by the skill itself.
Mailboxes, warmup and sending in one place
$2.50 a mailbox a month. DNS records are set for you, and every mailbox shows its warmup numbers from day one.