Privacy Policy

Last updated: November 14, 2026

Mailsnail prints and mails physical letters and certified mail on behalf of users and AI agents acting under their accounts. To do that we have to handle a small set of personal data. This policy is written to be short and unambiguous.

What we receive from AI assistants

When you use Mailsnail through an AI assistant, over our hosted MCP server, we receive only two things:

  • The tool call. This is what the assistant sends us to do a job: sender and recipient names and addresses, the letter text or a link to a PDF, and options such as certified mail, color or a description. If you give a PDF link, we download that file.
  • Your sign-in identity from the sign-in provider: a user ID, plus your name and email address when the provider includes them. See “Sign-in and connected assistants” below.

We do not receive your chat history or anything else from your conversation with the assistant. The assistant decides what goes into a tool call. What the AI platform itself keeps is governed by that platform's own privacy policy.

What we collect

  • Account data: your sign-in identity (an issuer and user ID), your name and email address when the sign-in provider supplies them, a hash of your API key (never the key itself), and, for company accounts, the team ID and name and which member authorized each piece. When you connect through an AI app, we also keep the name and version that app reports for itself (for example, Claude Code 2.1) and when it first and last connected.
  • Payment data: card details are collected by Stripe, not by us. We store Stripe's customer and payment references, your balance, a record of each top-up and deduction, and your auto-reload settings. A one-time payment does not save your card. If you opt in to auto-reload, we also store the saved card's brand, last four digits and expiry date, and when you agreed to auto-reload.
  • Mail records: for each piece, its type, price, date, the print supplier's job number, who authorized it, and the recipient's name and ZIP code. The full addresses and the letter itself go to our print supplier (see below). Our database does not store the text of your letters or the PDFs you send. Proofs are generated for your review and kept only in the server's memory; a proof link stops working after 30 minutes.
  • Usage logs: for each hosted-server tool call, the tool name, outcome and duration. For each REST API request, the time, endpoint, result, duration, and a shortened one-way hash of the caller's IP address (not the IP address itself), which we use to count distinct callers. We do not log letter text or tool arguments. Our hosting providers keep their own standard server logs.

What we do with it

  • Print and mail your letters and certified mail via USPS.
  • Operate and secure the service, investigate abuse, and help resolve problems with mail or payments.
  • Show your account history (mail you have sent and its delivery status).
  • Bill you for production mail.
  • Comply with legal obligations.

What we don't do

  • We don't sell your data.
  • We don't use mail content to train AI models.

Who we share data with

We share data only with the providers below, as needed to host and run Mailsnail, process payments, and print and deliver your mail.

  • Click2Mail (print and mail supplier) receives the letter content and the sender and recipient addresses. It also checks addresses for us. When you preview a letter, we send it to Click2Mail to create the proof, before you approve or pay.
  • USPS delivers your mail and sees the addresses on the piece.
  • Stripe processes payments and collects your card details directly. When you set up payment, we give Stripe your name and email address (when we have them) so the customer record matches your account. We never see your full card number.
  • WorkOS handles sign-in for the hosted server, including company accounts.
  • Railway hosts our API and database. Vercel hosts this website and provides its web analytics. We also keep our own count of visits to this website, and of a few actions on it (copying the connector address, following a link to the setup page or to an AI app): the page, the website that referred you, any campaign tag in the link, and whether the visit came from an automated crawler rather than a person. That count uses no cookies and does not record your IP address or your browser's details.
  • ImprovMX forwards email sent to hello@mailsnail.dev.
  • Meta is involved only if you choose Facebook sign-in.

Click2Mail and USPS keep records under their own policies, which we do not control. Your AI assistant and any self-hosted mail provider also process data you give them under their own policies.

We do not run our own print shop. Letters are printed, enveloped and handed to USPS by a third-party print and mail partner. Today that partner is Click2Mail (C2M LLC, Arlington, Virginia). We only use a print partner that meets all of the following:

  • Operates in the United States and hands mail to USPS directly.
  • Uses letter content and addresses solely to produce and deliver the mail you ordered, and does not sell, rent, trade or otherwise reuse them.
  • Publishes a privacy policy that treats the documents and addresses we send as data processed on our behalf, not as its own customer data.
  • Restricts physical access to its production facilities.
  • Receives from us only what the job needs: the letter PDF, the sender and recipient addresses, the mail options you chose and a short job description. It does not receive your account email, sign-in details or payment information.

The partner keeps job records under its own policy, which we do not control, and we cannot promise a specific deletion date for printed content held by the partner. If we add or change a partner, we update this section before routing any mail through it.

Retention

We keep account, payment, and send records for as long as we need them to fulfill mail, operate your account, provide support, reconcile payments, prevent duplicate sends and investigate abuse. We do not currently delete these records on a schedule, and we do not operate an automatic purge. Deletion requests are reviewed individually; financial, transaction, security and delivery records may need to be retained. We explain any retained categories when handling your request. Our print and delivery providers may also retain records under their own applicable policies.

Sign-in and connected assistants

WorkOS handles sign-in for the hosted server, including company accounts. From it we receive a user ID and, when the provider includes them, your name and email address, plus a team ID and name for company accounts. We identify your account by the user ID, not by your email address.

Where Facebook sign-in is offered, Meta supplies an app-specific Facebook ID and your public profile name. We request only Facebook's public profile permission: not your email address, friends or posts. We store the Facebook ID, your name, a placeholder internal address (it is not an email address we can write to), your sign-in sessions, the permissions you grant to assistants, and your Facebook sign-in credentials in encrypted form. We do not combine Facebook and company accounts by matching email addresses. If you later set up payment, your name is sent to Stripe as described above.

Signing out of a browser does not necessarily disconnect an assistant. Where available, use Disconnect all assistants in your MailSnail account, or remove MailSnail from Facebook's connected apps. Disconnecting removes that connection's authority; it does not delete your account, change separate API-key or WorkOS access, change automatic billing settings, or cancel mail already accepted for sending.

Request access, correction or deletion

Email hello@mailsnail.dev with the subject "MailSnail data request". Tell us whether you want access, a correction, deletion, or account closure. Include an account identifier or an order reference if you have one. If you signed in with Facebook and do not know an account email, say so. Never email a password, full API key, access token or card number.

We verify control of the affected account before acting. An email address alone does not prove ownership of a Facebook identity or authority over a company account. We review outstanding mail, payments and any records that need to be retained, and explain the outcome. Removing the Facebook connection alone is not a request to delete all MailSnail data. You can use the same contact address for privacy questions and requests under applicable privacy laws.

Changes

We'll update this page when the policy changes and post the new effective date above.

Contact

hello@mailsnail.dev