# When a letter is the right choice, and how to send it.

E-mail is often enough. These guides say when a letter is better, what the post records, what it does not prove, and what it costs. Each one has its sources.

- [Send a registered letter to Belgium](https://agentletterdesk.com/guides/registered-letter-to-belgium): Registered letter to Belgium from your AI app: bpost records the posting and the delivery. €13.90, preview first, no post office. Markdown: https://agentletterdesk.com/guides/registered-letter-to-belgium.md
- [Send a registered letter to Spain](https://agentletterdesk.com/guides/registered-letter-to-spain): Registered letter with signature to Spain from your AI app: Correos carta certificada for €8.90. Check the preview first. No post office. Markdown: https://agentletterdesk.com/guides/registered-letter-to-spain.md
- [Send a real letter from Claude](https://agentletterdesk.com/guides/send-letter-from-claude): Add Agent Letter Desk to Claude once. Claude writes the letter with you, you approve preview and price, we print and post it. 31 countries. Markdown: https://agentletterdesk.com/guides/send-letter-from-claude.md
- [Send a registered letter from ChatGPT](https://agentletterdesk.com/guides/send-registered-letter-from-chatgpt): Connect once, ask ChatGPT, check the preview and price, say yes. We print and post it. Registered mail to the US, Germany, Belgium and Spain. Markdown: https://agentletterdesk.com/guides/send-registered-letter-from-chatgpt.md

[These guides in German](https://agentletterdesk.com/de/ratgeber)

## Use it with Claude, ChatGPT, Grok or Mistral Vibe

Add Agent Letter Desk to your AI app once, with this server URL: `https://agentletterdesk.com/mcp`

- **Claude** (claude.ai, desktop and mobile): [Add to Claude](https://claude.ai/customize/connectors?modal=add-custom-connector&connectorName=Agent%20Letter%20Desk&connectorUrl=https%3A%2F%2Fagentletterdesk.com%2Fmcp) opens Claude with the name and the URL filled in. Select Add, then Connect. Sign in and allow access, then turn the connector on in a chat. By hand: Settings › Connectors › Add custom connector, then paste the URL.
- **ChatGPT** (chatgpt.com): Plugins › Add › Add custom MCP server. Paste the URL, choose OAuth, sign in and allow access. Custom MCP servers are not available on every ChatGPT plan.
- **Grok** (grok.com): Plugins (Connectors) › New connector › Custom. Enter a name and paste the URL. Sign in and allow access in the window that opens. In a chat, type @ and pick Agent Letter Desk (Grok uses a connector only when you select it).
- **Mistral Vibe** (chat.mistral.ai, formerly Le Chat): Connectors › Add custom connector. Enter a name without spaces, such as AgentLetterDesk, and paste the URL. Sign in and allow access. In a chat, select + › Connectors › Agent Letter Desk (without this step, Mistral Vibe may write the letter itself). Works on the free plan.

You sign in with your e-mail address or your Google account. Before the launch, only invited testers can create an account. Everyone else can join the waitlist: https://agentletterdesk.com/waitlist. Then ask your AI for the letter. You check the preview and the price. Nothing goes out without your yes.

Prices, destinations and the rules for every letter: [All prices and destinations](https://agentletterdesk.com/#destinations) · [How it works](https://agentletterdesk.com/#how) · [Safeguards](https://agentletterdesk.com/#safeguards) · [Terms](https://agentletterdesk.com/terms) · [Full facts for AI agents](https://agentletterdesk.com/llms-full.txt)