email_validation

email_validation is a skill for Claude Code from nikhilreddy3888/public-api-toolkit. It costs 32 tokens per session (334 once invoked), scanned A, original, MIT.

An email-checking tool that examines an address’s format, domain, and MX records. MX records identify the mail servers that receive email for a domain; it can also detect disposable and free-provider addresses.

In plain words
What is it for?
Use it to validate signup emails, check whether a domain can receive mail, identify disposable addresses, or filter free email providers.
Why use it?
It helps catch mistyped, undeliverable, or temporary addresses before they enter a mailing list or signup form.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the public-api-skills plugin — 43 skills shipped together

Good fit Use it to validate signup emails, check whether a domain can receive mail, identify disposable addresses, or filter free email providers.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nikhilreddy3888/public-api-toolkit/email_validation
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.

Any agent
npx skills add nikhilreddy3888/public-api-toolkit --skill email_validation
Clone the repo
git clone --depth 1 https://github.com/nikhilreddy3888/public-api-toolkit

Made for: Claude Code.

Or install public-api-skills, the plugin that ships this one along with the rest of its 43 skills.

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.

agentmods badge for email_validation

README.md
[![agentmods](https://agentmods.dev/badge/skills/nikhilreddy3888/public-api-toolkit/email_validation.svg)](https://agentmods.dev/skills/nikhilreddy3888/public-api-toolkit/email_validation)
Your own site
<a href="https://agentmods.dev/skills/nikhilreddy3888/public-api-toolkit/email_validation"><img src="https://agentmods.dev/badge/skills/nikhilreddy3888/public-api-toolkit/email_validation.svg" alt="Measured on agentmods" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 334 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00032 $0.00334
Opus 5 $0.00016 $0.00167
Sonnet 5 $0.00006 $0.00067
Haiku 4.5 $0.00003 $0.00033

Measured 7d ago against content hash ab46fcf87af0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

email_validation 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 7d 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_validation/SKILL.md · 59 lines

What it actually says

Email Validation

Real-time email address verification with MX record checking.

APIs

mailvalidate.org

  • Endpoint: https://mailvalidate.org/api/validate
  • Method: GET
  • Auth: None (free tier: 20/hour)
  • Docs: https://mailvalidate.org/
Parameter Type Description
email string Email address to validate

disposableemailchecker.com

Example Queries

Response

{
  "email": "[email protected]",
  "valid": true,
  "format_valid": true,
  "domain_valid": true,
  "mx_records": ["mail.example.com"],
  "is_disposable": false,
  "is_free_provider": false
}

Use Cases

  • Form validation on signup
  • Detect disposable/temporary emails
  • Verify email deliverability
  • Filter free provider emails (gmail, yahoo)

Token Savings

15-30x vs LLM reasoning for email validation.

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.

  1. 7d ago First seen · 59 lines · 32 tokens per session scan A ab46fcf87af0

Subscribe to this mod's changes

email_validation is a skill published in the GitHub repository nikhilreddy3888/public-api-toolkit (2 stars, last pushed 4mo ago), licensed MIT. It adds 32 tokens to every session and 334 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 2026-08-31.

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