MCP.Market

Mailsnail MCP server

by iancollins27·io.github.iancollins27/mailsnail·v0.6.0
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Send USPS letters, postcards & certified mail from any agent. No signup; pay-per-piece via Stripe.

B78/100grade B
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Safety scan
B78/100

full report

Adoption
New

0 stars33 downloads/wk

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If you have run it, two minutes of your experience saves the next person an afternoon.

Mailsnail tools (7, 3 write)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

  • cancel_letterwrite action

    Cancel a letter before it enters production. Cancellation windows are short and provider-specific.

  • get_letter

    Fetch the status of a previously sent letter by id.

  • list_letters

    List recent letters (Lob only — Click2Mail does not expose a list endpoint).

  • preview_letter

    Generate a PROOF of a letter WITHOUT charging or mailing. Returns `proof_url` (a viewable PDF of exactly what will be printed and mailed, including the address cover sheet), the CASS-verified recipient address, the exact price, and a `draft_id`. Best practice: call this FIRST, show the user the proof_url and price, get explicit confirmation, then call send_letter with the returned draft_id + a pay

  • send_letterwrite action

    Send a physical letter via USPS. RECOMMENDED FLOW: first call preview_letter, show the user the returned proof_url + price, get explicit confirmation, then call send_letter with the returned `draft_id` and a `payment_token` — this charges and mails exactly the proofed letter. You may also send one-shot by providing the full letter (to, from, and body_text or file_url) plus payment_token, without a

  • send_postcardwrite action

    Send a physical postcard. Provide a public URL to a PDF (front + back combined for Click2Mail; separate front/back for Lob).

  • verify_address

    Verify and normalize a US mailing address. Run this on user-provided addresses before sending mail.

Public scan report

scanner v0.1.9 · 2026-09-25 · same rubric, same numbers if you re-run it

no findings
  • Code scan3 source files scanned25/25
  • –Live reliabilityno gateway calls yet and no remote to proben/a
  • –Tool poisoningtools not inspected (local package is not executed); not countedn/a
  • Auth qualitystatic API keys via environment variables6/15
  • Maintenancelast push 39 days ago12/15
  • Maintainer identityregistry namespace matches repository owner; GitHub account older than a year8/10
Overall 78/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Mailsnail compares

Against every graded E-commerce MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
78/100
higher than 67% of 2,174 E-commerce servers
Tools
7
the typical E-commerce server has 6
Tools that change things
43%
typical: 0%. Fewer write tools means less an agent can break
Downloads a week
33
more than 25% of 411 E-commerce servers with a package

What its tools let an agent do: 4 read · 1 delete · 2 send or post

Install Mailsnail in Claude Code, Cursor or VS Code

Runs npx -y mailsnail on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add mailsnail -- npx -y mailsnail
Add to Cursor

What the publisher says

From the Mailsnail repository's README, as published. We do not edit it. Read it on GitHub

Mailsnail

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:

  • No signup in managed mode. Agents pay per piece via Stripe Shared Payment Tokens over the Machine Payments Protocol (HTTP 402). First letter can go out minutes after install. $1.50 first-class, $9.00 certified, $1.00 postcard — flat, no subscription.
  • 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 extraservice: "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.
claude mcp add mailsnail -- npx -y mailsnail
# then: "Send me a postcard that says hello."

Packages

Four ways to run it

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:

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

Allow this host:

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Mailsnail: common questions

Is Mailsnail MCP server safe?
Mostly: it is graded B (78/100). Read the Mailsnail safety report
How do I install Mailsnail?
It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Mailsnail need an API key?
Yes. The registry entry asks for CLICK2MAIL_PASSWORD, LOB_API_KEY.
Is Mailsnail maintained?
The last commit was 78 days ago (2026-08-17). The latest release is v0.6.0.
What can I use instead of Mailsnail?
Servers from other publishers that do the same job: Stripe MCP server, Stripe Acp MCP server and GenesisPay MCP server.
How does Mailsnail compare with other E-commerce MCP servers?
safety score 78/100 (higher than 67% of 2,174 E-commerce servers); tools 7 (the typical E-commerce server has 6); tools that change things 43% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.

Alternatives to Mailsnail

Same job from other publishers: the closest match first, then the best rated.

  • Stripe
    MCP server integrating with Stripe - tools for customers, products, payments, and more.
    A
  • Stripe Acp
    Stripe ACP — AI agent checkout, payment delegation, products, invoices
    More from codespar →
    B
  • GenesisPay
    Let an AI agent find and pay for x402 APIs and products in USDC on Base, within owner-set limits.
    C
  • Email
    Send email through your own Amazon SES account, and check domains, suppressions and sandbox status.
    A
  • Vectros AI
    Typed record store + hybrid search over MCP: deterministic lookups + semantic memory, per-customer.
    B