mailagent

A service that gives coding agents disposable email inboxes for testing signups, logins, and email verification.

In plain words
What is it for?
Use it to register test accounts, retrieve verification codes or magic links, send or reply on approved domains, and investigate email-delivery timeouts.
Why use it?
It avoids manually opening email messages or parsing their HTML to find one-time passwords and login links. It also lets tests receive simulated email without using a real mail server.

Skill for Claude CodeCodex

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/hashgraph-online/awesome-codex-plugins/mailagent
Any agent
npx skills add hashgraph-online/awesome-codex-plugins --skill mailagent
Clone the repo
git clone --depth 1 https://github.com/hashgraph-online/awesome-codex-plugins

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,323 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.

ModelPer sessionOnce invoked
Fable 5 $0.00043 $0.03323
Opus 5 $0.00022 $0.01662
Sonnet 5 $0.00009 $0.00665
Haiku 4.5 $0.00004 $0.00332

Measured 3d ago against content hash 342745ffa80e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mailagent 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 3d 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.

plugins/Alex0nder/MailAgent/skills/mailagent/SKILL.md · 257 lines

How it starts

The opening of the file, as written. The whole thing — 257 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MailAgent

MailAgent provides programmatic disposable inboxes for AI agents: receive OTP codes and magic links during signup flows, simulate inbound mail in CI, send/reply on verified domains, and diagnose timeouts.

Official docs: https://webmailagent.com/docs/agents.html

When to use

  • Signup or login that sends a verification email
  • Need OTP or magic link without hand-parsing HTML
  • E2E / agent task: "register with a temp email"
  • QA without real SMTP (mailagent_simulate_message)
  • Not for human privacy burners — programmatic agent inboxes with allowlists

Install (pick one)

Cursor (project)

MCP in .cursor/mcp.json@mailagent/mcp or mcp/dist/index.js. Skill auto-loads from .cursor/skills/mailagent-mcp/ (synced from this file).

Agent Skills catalog (repo root)

npx skills add Alex0nder/MailAgent --skill mailagent

OpenAI Codex

codex plugin marketplace add Alex0nder/MailAgent
codex plugin add mailagent@mailagent

Guide: https://webmailagent.com/docs/codex.html

npm MCP (any client)

export MAILAGENT_API_URL=https://api.webmailagent.com
export MAILAGENT_API_KEY=ma_…
npx -y -p @mailagent/[email protected] mailagent-mcp

Remote (no subprocess): POST https://api.webmailagent.com/mcp + Bearer token.

SDK (without MCP)

Package Install
@mailagent/agent npm install @mailagent/agent
@mailagent/qa npm install @mailagent/qa (Playwright)
mailagent-agent pip install mailagent-agent (Python)

Browser login (no API key in client): Auth0 OIDC on prod — auth.oidc: enabled on GET /v1/agent. Operator setup: npm run wizard:auth0. Docs: https://webmailagent.com/docs/oauth-idp.html

Prerequisites

  • MAILAGENT_API_KEYconsole dashboard team keys, or MailAgent repo npm run issue:key:db when self-hosting
  • MCP server mailagent connected (codex mcp list / Cursor MCP refresh)
  • Always set service preset or expectFrom (sender allowlist)

Read the full file on GitHub · 257 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.

  1. 3d ago First seen · 257 lines · 43 tokens per session scan A 342745ffa80e

Subscribe to this mod's changes

mailagent is a skill published in the GitHub repository hashgraph-online/awesome-codex-plugins (859 stars, last pushed 4d ago), licensed Apache-2.0. It adds 43 tokens to every session and 3,323 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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