Is the Cold Email Verifier skill free?

Yes. The skill itself is free from Varnan-Tech/opendirectory. SkillProof publishes the install command and an independent test verdict at no cost.

What is the Cold Email Verifier SkillProof Score?

8.0/10 — installs cleanly 5/5, triggers reliably 5/5, output vs. baseline 6/10, docs & honesty 4/5.

How do I install Cold Email Verifier?

Copy the install command from this page, run it in your terminal, and restart Claude Code. Skills live in ~/.claude/skills/ (global) or .claude/skills/ inside a project.

Can I use Cold Email Verifier with Cursor, Copilot, Gemini CLI, Codex or other AI tools?

The SKILL.md format is native to Claude (Claude Code, Desktop, claude.ai). The instructions inside adapt to other assistants: Cursor rules, GitHub Copilot instructions, Windsurf rules, Custom GPTs, AGENTS.md for OpenAI Codex, and GEMINI.md for Google Gemini CLI — our conversion guides cover each, and the free converter on the tools page does the wrapping for you.

Cold Email Verifier

Guesses corporate email permutations from a lead CSV and verifies deliverability

by Varnan-Tech · Varnan-Tech/opendirectory

Works with setup

Install — copy the command Download source ↗

Test report

Verdict: Works with setup
Score: 8.0/10
Tested: Jul 21, 2026
Environment: Claude Code 2.x (agent harness)
Upstream re-checked: Aug 10, 2026 · 38908a4

Cloned the repo, confirmed all body-referenced files exist (SKILL.md, scripts/email_verifier.py, requirements.txt, .env.example all HTTP 200; requests+pandas installed locally). Ran email_verifier.py in its --test mode on a deliberately messy 2-row CSV: it correctly normalized the domain https://www.acme.com/about to acme.com and stripped the hyphen from Marie-Claire, but coerced an empty Last Name into the string "nan", emitting junk perms john.nan@stripe.com and johnnan@stripe.com. Baseline (hand-generated) would output john@stripe.com only, so the script wins on URL/punctuation normalization but has a real empty-field bug. Verdict setup because actual verification (the skill's core) needs a ValidEmail.co API key or a self-hosted Reacher server with port 25, neither runnable here; only the guessing engine was measured. No security smells: keys read from env, endpoints are the documented Clearbit/ValidEmail/localhost, no curl|sh or exfiltration.

Scored on four weighted criteria — install, triggering, output vs. baseline, docs. How scoring works

Installs cleanly 5/5
Triggers reliably 5/5
Output vs. baseline 6/10
Docs & honesty 4/5

What Cold Email Verifier does

A Python skill that reads a CSV of leads (First Name, Last Name, Company Name), resolves each company's domain via the Clearbit autocomplete API, generates three common email permutations, and verifies deliverability through the ValidEmail.co API or a self-hosted Reacher backend. Triggers when the user asks to verify cold emails, guess email addresses from names/companies, or enrich a lead list. Verification requires a ValidEmail.co API key or a self-hosted Reacher server with outbound port 25.

How to install Cold Email Verifier

git clone --depth 1 https://github.com/Varnan-Tech/opendirectory.git /tmp/cold-email-verifier-src
mkdir -p ~/.claude/skills
cp -R /tmp/cold-email-verifier-src/skills/cold-email-verifier ~/.claude/skills/cold-email-verifier
# Python deps: pip install -r ~/.claude/skills/cold-email-verifier/requirements.txt   (requests, pandas)
# Verification needs EITHER a ValidEmail.co API key: export VALIDEMAIL_API_KEY="..."  (--mode validemail)
#   OR a self-hosted Reacher backend with outbound port 25 open (--mode reacher-http --reacher-url http://IP:8080/v0/check_email)
# Permutation generation alone runs offline with no key: python scripts/email_verifier.py --input leads.csv --output out.csv --mode validemail --test
# Plugin-marketplace alternative: /plugin marketplace add Varnan-Tech/opendirectory ; /plugin install opendirectory-gtm-skills@opendirectory-marketplace

Skills live in ~/.claude/skills/ (global) or .claude/skills/ (per-project). Restart Claude Code after installing.

Commands — how to trigger Cold Email Verifier

/cold-email-verifier Guesses corporate email permutations from a lead CSV and verifies deliverability

It also activates on plain-language prompts like these:

Verify the emails in this lead CSV
Guess email addresses for these contacts
Enrich this lead list with verified emails

Frequently asked questions

Is the Cold Email Verifier skill free?: Yes. The skill itself is free from Varnan-Tech/opendirectory. SkillProof publishes the install command and an independent test verdict at no cost.
Does Cold Email Verifier work with Claude Code?: We tested it with Claude Code 2.x (agent harness) on Jul 21, 2026. Verdict: Works with setup. Cloned the repo, confirmed all body-referenced files exist (SKILL.md, scripts/email_verifier.py, requirements.txt, .env.example all HTTP 200; requests+pandas installed locally). Ran email_verifier.py in its --test mode on a deliberately messy 2-row CSV: it correctly normalized the domain https://www.acme.com/about to acme.com and stripped the hyphen from Marie-Claire, but coerced an empty Last Name into the string "nan", emitting junk perms john.nan@stripe.com and johnnan@stripe.com. Baseline (hand-generated) would output john@stripe.com only, so the script wins on URL/punctuation normalization but has a real empty-field bug. Verdict setup because actual verification (the skill's core) needs a ValidEmail.co API key or a self-hosted Reacher server with port 25, neither runnable here; only the guessing engine was measured. No security smells: keys read from env, endpoints are the documented Clearbit/ValidEmail/localhost, no curl|sh or exfiltration.
What is the Cold Email Verifier SkillProof Score?: 8.0/10 — installs cleanly 5/5, triggers reliably 5/5, output vs. baseline 6/10, docs & honesty 4/5.
How do I install Cold Email Verifier?: Copy the install command from this page, run it in your terminal, and restart Claude Code. Skills live in ~/.claude/skills/ (global) or .claude/skills/ inside a project.
Can I use Cold Email Verifier with Cursor, Copilot, Gemini CLI, Codex or other AI tools?: The SKILL.md format is native to Claude (Claude Code, Desktop, claude.ai). The instructions inside adapt to other assistants: Cursor rules, GitHub Copilot instructions, Windsurf rules, Custom GPTs, AGENTS.md for OpenAI Codex, and GEMINI.md for Google Gemini CLI — our conversion guides cover each, and the free converter on the tools page does the wrapping for you.