Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Varnan-Tech/opendirectory --skill cold-email-verifiergit clone --depth 1 https://github.com/Varnan-Tech/opendirectoryWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/varnan-tech/opendirectory/cold-email-verifier)<a href="https://agentmods.dev/skills/varnan-tech/opendirectory/cold-email-verifier"><img src="https://agentmods.dev/badge/skills/varnan-tech/opendirectory/cold-email-verifier.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.00738 |
| Opus 5 | $0.00020 | $0.00369 |
| Sonnet 5 | $0.00008 | $0.00148 |
| Haiku 4.5 | $0.00004 | $0.00074 |
Grade A, and why
cold-email-verifier scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cold Email Verifier and Guesser (Public)
Overview
This skill autonomously processes a CSV of leads (containing First Name, Last Name, and Company Name), discovers their corporate domain, generates professional email permutations, and strictly verifies their deliverability.
It is designed to solve the problem of missing contact info by guessing core email angles and then checking which one is real.
The Email Guessing Engine
You don't need to provide emails in your CSV! If the CSV only contains First Name, Last Name, and Company Name, the script will automatically:
- Look up the company's official domain using the free Clearbit API.
- Clean the names (removing punctuation) and generate the 3 most common corporate email formats:
Verification Methods (Choose Your Engine)
Once the emails are guessed, the script must verify them. We support three methods:
1. ValidEmail.co API (Highly Recommended)
The absolute best option. ValidEmail.co provides enterprise-grade accuracy, bypasses strict catch-all servers, and handles IP reputation for you.
- Free Tier: They offer a generous free tier (50 free verification credits on signup) to get you started!
- How to use: Go to validemail.co, create an account, get your API key, and run the script in --mode validemail.
2. Reacher Open Source (Self-Hosted)
If you want a 100% free, open-source solution, you can host the Reacher backend yourself on a cloud provider (like AWS, GCP, or Hetzner).
- GitHub Repo: reacherhq/check-if-email-exists
- Important: Your cloud provider MUST have outbound Port 25 open.
- How to use: Host the docker container, then run the script using --mode reacher-http --reacher-url "http://<YOUR_SERVER_IP>:8080/v0/check_email".
3. Reacher Local CLI (Not Recommended / Unreliable)
You can run the Reacher CLI directly on your laptop.
- Warning: Residential ISPs globally block Port 25 to prevent spam. Furthermore, major mail servers (Microsoft, Google) will automatically reject SMTP handshakes from residential Wi-Fi IP addresses.
- Result: You will get massive amounts of false negatives and timeouts. Use ValidEmail.co instead.
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 60 lines · 41 tokens per session scan A 73c882c98855
cold-email-verifier is a skill published in the GitHub repository Varnan-Tech/opendirectory (635 stars, last pushed 22d ago), licensed MIT. It adds 41 tokens to every session and 738 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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