What is email-verifier?

An email-checking tool that assesses whether an address can receive mail by checking its domain and mail-server records. DNS and SMTP are internet systems used to locate and communicate with mail servers.

Use it to verify one or more email addresses and review their deliverability status before sending.

It helps detect addresses that may bounce before you send messages to them.

email-verifier — Skill for Claude Code and Codex by hunter-io: An email-checking tool that assesses whether an address can…

Install

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.

agentmods

npx agentmods add skills/hunter-io/claude-plugin/email-verifier

Any agent

npx skills add hunter-io/claude-plugin --skill email-verifier

Clone the repo

git clone --depth 1 https://github.com/hunter-io/claude-plugin

Made for: Claude Code, Codex.

Or install hunter, the plugin that ships this one along with the rest of its 13 skills, 1 MCP server.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/hunter-io/claude-plugin/email-verifier.svg)](https://agentmods.dev/skills/hunter-io/claude-plugin/email-verifier)

Your own site

<a href="https://agentmods.dev/skills/hunter-io/claude-plugin/email-verifier"><img src="https://agentmods.dev/badge/skills/hunter-io/claude-plugin/email-verifier.svg" alt="Measured on agentmods" height="20"></a>

Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 655 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00045	$0.00655
Opus 5	$0.00023	$0.00328
Sonnet 5	$0.00009	$0.00131
Haiku 4.5	$0.00005	$0.00065

Measured 5d ago against content hash 5ec5d74033f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 5d 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.

skills/email-verifier/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Email Verifier

Check whether an email address is deliverable before you send to it.

Examples

/hunter:email-verifier [email protected]
"Is [email protected] a valid email?"
"Check if [email protected] is deliverable"
"Verify these emails: [email protected], [email protected], [email protected]"
"Can I send to [email protected]?"

Steps

Parse the input. Extract the email address(es).
Call Email-Verifier for each email.
Present the result with an actionable recommendation:

# Verification: [email protected]

| Check | Result |
|-------|--------|
| **Status** | valid |
| **Score** | 91 |
| **MX Records** | Valid |
| **SMTP Check** | Valid |
| **Accept All** | No |
| **Disposable** | No |

## Recommendation
Safe to send. This email address is deliverable with high confidence.

## Next Actions
1. Find more contacts at stripe.com
2. Enrich this contact with personal details

Interpret the result clearly based on the status field:
- valid (score 80+) -> "Safe to send. This email address is deliverable with high confidence."
- accept_all -> "Proceed with caution. This mail server accepts all addresses, so delivery is not guaranteed even though SMTP checks pass."
- unknown -> "Unable to determine deliverability. The mail server didn't respond clearly -- consider sending a low-priority test first."
- invalid (score below 50) -> "Do not send. This address is likely invalid and will bounce."
- Disposable email (disposable: true) -> Add: "This is a disposable/temporary email address. It may stop working at any time."
- Pending (HTTP 202 response) -> "Verification is still in progress. Try again in a few seconds."
For multiple emails, verify each separately and present a summary:

# Verification Summary

| Email | Status | Score | Recommendation |
|-------|--------|-------|----------------|
| [email protected] | valid | 91 | Safe to send |
| [email protected] | accept_all | 62 | Proceed with caution |
| [email protected] | invalid | 12 | Do not send |

**Results:** 1 valid, 1 accept_all, 1 invalid

Read the full file on GitHub · 77 lines

Changes

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.

5d ago First seen · 77 lines · 45 tokens per session scan A 5ec5d74033f1

Subscribe to this mod's changes

email-verifier is a skill published in the GitHub repository hunter-io/claude-plugin (9 stars, last pushed 3d ago), licensed MIT. It adds 45 tokens to every session and 655 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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