Mailsnail

io.github.iancollins27由 GitHub 账号 iancollins27 发布v0.6.1更新于 Nov 7, 2026

Send USPS letters & certified mail from any agent. Hosted: sign in, no install.

已验证Streamable HTTP可网页运行效率与工作流商业与电商

概览

AI 生成的概览

让助手校验地址、预览样张并寄出真实的 USPS 平信、挂号信和明信片，可用托管服务或自建部署。

可以做什么
  • 校验收件地址，并在寄出前生成样张 PDF 与准确报价
  • 寄送平信、挂号信和明信片，并查询、列出或取消已寄邮件
  • 查询账户余额并为托管寄送充值
  • 诊断网络连通性与服务商配置
  • 在托管服务、自有 Click2Mail 或 Lob 账户、自建网关与故障转移之间选择
适用场景
当助手需要把纸质信件真正投递到美国邮箱时使用，例如日常通信，或必须寄出并可追踪的挂号法律通知。托管连接器适合不想安装、也不想申请服务商账户的用户。
运行要求
使用远程端点并通过 OAuth 登录，或在本地用 Node.js 运行 npm 包。自建需设置 MAIL_PROVIDER 及服务商凭据：CLICK2MAIL_USERNAME 与 CLICK2MAIL_PASSWORD，或 LOB_API_KEY；托管模式需 MAIL_API_BASE_URL。需要能访问服务商或网关主机的网络。
安装前请注意
寄信会真实花钱：托管模式按封用卡支付或从余额扣款，自带凭据模式则计入你的服务商账户。实际寄出需设置 MAIL_MCP_ALLOW_LIVE=1，建议保持默认演练并设置 MAIL_MCP_SPEND_CAP_USD。服务商密钥以环境变量传入。邮件一旦进入生产环节便无法撤回，且须遵守 USPS 规定与服务商条款。

安装

在 SourceWeft 中

  1. 打开 控制台中的 Mailsnail，将其添加到工作区。
  2. 连接 所需的 凭据。它们会被私密存储，绝不会在公开页面上展示。
  3. 为需要使用其工具的对话启用该服务。

Web executable，通过 Streamable HTTP。 远程服务在工作区中配置后即可从网页运行时运行。

交给智能体安装

把这段提示词粘贴到 Claude Code、Codex、Cursor 等智能体，或 SourceWeft 对话中。智能体会读取该服务器的安装指南，先向你展示发布者、端点和登录方式，经你同意后再把它添加到你的客户端。密钥不会写进任何命令。

阅读 https://sourceweft.com/mcp/io.github.iancollins27%2Fmailsnail/install.md，并按其中说明把这个 MCP 服务器接入我的客户端。修改任何配置之前，先告诉我它的发布者、端点和登录方式，等我确认。不要把 API 密钥写进命令或我会提交的文件；问我密钥应从哪里获取。

查看智能体所依据的安装指南

其他 MCP 客户端

把它添加到你客户端的 mcpServers 配置中。 客户端会在首次连接时完成 OAuth 登录。

{
  "mcpServers": {
    "mailsnail": {
      "type": "http",
      "url": "https://api.mailsnail.dev/mcp"
    }
  }
}

README

[Mailsnail]

Mailsnail

[smoke]

Open-source, provider-agnostic physical mail for AI agents.

Agents have every channel except one. They can email, text, call, and post to every feed — but until now, putting a real, postmarked envelope in a mailbox meant a human signing up for a print-provider account, provisioning API keys, and wiring billing. Mailsnail closes that gap:

  • Nothing to install. Add one URL to Claude, ChatGPT, Cursor or any MCP client and sign in. Pay for one letter by card or fund a balance, priced at our cost: from $1.21 first-class and $8.61 certified, no subscription. Agents that can mint a Stripe Shared Payment Token can also pay per piece with no account, over the Machine Payments Protocol (HTTP 402).
  • No lock-in, ever. The provider layer is open and swappable: bring your own Click2Mail or Lob account, self-host the whole gateway, or chain providers for failover. The managed service is a convenience, not a cage.
  • Built for compliance mail. Certified letters with extra_service: "certified" — the mail that legally must be physical (preliminary lien notices, legal notices) and must not miss its deadline because one print API had a bad day.
bash
claude mcp add -t http mailsnail https://api.mailsnail.dev/mcp# then /mcp → mailsnail → Authenticate, and: "Mail a thank-you letter to my aunt."

In Claude Desktop or ChatGPT, add https://api.mailsnail.dev/mcp as a custom connector. Steps for every app: mailsnail.dev/setup. Running your own Click2Mail or Lob account instead? See Ways to run it.

Hosted connector and plugins

The quickest start needs no install. Add https://api.mailsnail.dev/mcp as a custom connector in Claude, ChatGPT, Cursor or any MCP client that supports remote servers, then sign in. Each app's setup steps are at mailsnail.dev/setup.

plugins/mailsnail packages that connector with skills for sending letters, sending certified mail and tracking mail. It works in Claude (chat, Cowork and Claude Code) and in Cursor. To install it in Claude Code:

text
/plugin marketplace add iancollins27/mailsnail/plugin install mailsnail@mailsnail

Packages

PackageWhat it is
mailsnailMCP server — 11 tools (doctor, verify_address, preview_letter, send_letter, send_postcard, get_balance, top_up, get_letter, get_postcard, list_letters, cancel_letter) over any provider below. Works in Claude Code, Claude Desktop, Cursor, Codex CLI, OpenAI Agents SDK.
@mailsnail/coreProvider-agnostic core: adapters (Click2Mail, Lob, any Mailsnail gateway), multi-provider failover router, request validation. Zero dependencies.
@mailsnail/gatewaySelf-hostable REST API: BYO provider credentials, body_text→PDF rendering, proofs, invocation logging. The managed service at api.mailsnail.dev runs the same wire protocol.
spec/The provider-neutral mail-piece schema + the failover-safety contract. Implement it and anything — including a print shop — becomes a Mailsnail-compatible node.

Ways to run it

ModeCredentialsPayingGood for
hosted connector (api.mailsnail.dev/mcp)none; you sign inyou, per letter by card or from a balancepeople in Claude, ChatGPT, Cursor; zero-setup
managed (stdio default)noneagent, per piece (Stripe SPT)agents that can mint an SPT
gatewayyour own, on your serveryour provider accountteams; PII stays in your infra
click2mail / lob (BYOK)yours, local envyour provider accountdirect control, one provider
failover chainyours, per provideryour provider accountsmail that must not miss deadlines

Failover is deliberately conservative: a send moves to the next provider only when the failed provider guarantees nothing entered production and no money moved (safeToRetry — see the spec). A duplicate certified letter is worse than an error.

Running behind an egress proxy or allowlist

Sandboxed agents — CI runners, enterprise agent platforms, hosted agent sessions — usually sit behind an egress allowlist, and that is the environment managed mode is for. Two minutes of setup:

bash
npx mailsnail doctor      # says exactly what it can and can't reach, and why. Free; never mails.

Allow this host:

ModeHost to permitPort
managed (default)api.mailsnail.dev443 (TCP / HTTPS CONNECT)
self-hosted gatewaywhatever MAIL_API_BASE_URL points atits port
click2mail (BYOK)rest.click2mail.com443
lob (BYOK)api.lob.com443

Allowlist by hostname, not IP: the managed gateway runs on managed infrastructure and its addresses change without notice. If your policy is IP-only, self-host @mailsnail/gateway on an address you control — that escape hatch is the whole point of the open provider layer.

Through an HTTP proxy. Node's fetch ignores HTTPS_PROXY unless you tell it not to, so an allowlisted gateway can still time out silently. Either:

bash
export NODE_USE_ENV_PROXY=1        # Node >= 22.21export HTTPS_PROXY=http://proxy.example:8080

or install undici alongside mailsnail (npm i undici) and Mailsnail routes through HTTPS_PROXY/HTTP_PROXY/ALL_PROXY itself, honoring NO_PROXY. mailsnail doctor tells you which of these is actually in effect.

TLS-inspecting proxy? Point NODE_EXTRA_CA_CERTS at your organization's CA bundle.

When it's blocked anyway, the failure says so instead of guessing: transport errors carry a code of unreachable, egress_blocked, or tls_untrusted, plus the exact host:port to permit. Any of those codes means the request never reached the backend — nothing mailed, nothing was charged, and the fix is network policy, not your account.

Safety

  • Dry-run by default everywhere; live mail requires an explicit MAIL_MCP_ALLOW_LIVE=1.
  • Per-session spend caps in the MCP server; auto-refund in managed mode when a paid piece fails to mail.
  • preview_letter returns a proof PDF and exact price before anything is charged — show it to your user first.
  • Don't use this for spam, harassment, or fraud. Provider terms and USPS regulations apply; managed mode enforces its own abuse screening.

Why open source

You're letting software put paper in mailboxes and spend money doing it. Read the code. Run it yourself with your own provider account for free. Use managed mode when you'd rather not hold credentials at all. If we ever disappoint you, MAIL_PROVIDER=click2mail and your mail keeps moving — that's the deal, and it's enforceable because this repo exists.

Status

Early. US-only today. Letters, certified letters, and postcards. The managed API, MCP server, self-host gateway, and Click2Mail/Lob adapters are live; additional adapters (PostGrid, Stannp) are next — CONTRIBUTING.md has the adapter guide if you want one sooner.

License

MIT.

来源：README.md，提交 6367d26

工具

0
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版本历史

2
  1. v0.6.1最新Nov 7, 2026
  2. v0.6.0Sep 16, 2026

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