About send0
send0 is an MCP server that gives AI agents dedicated email inboxes for account sign-ups and real conversations. It combines verification-code and link extraction with thread-based reading and replies.
Key features
- 01Create and list inboxes
- 02Wait for email with codes and links extracted
- 03Search and read messages
- 04Read email threads
- 05Send emails and reply in threads
- 06Flag prompt-injection messages
Use cases
- 01Complete account sign-ups requiring email verification
- 02Find a message from a specific sender
- 03Review a full email conversation
- 04Send a reply from an agent inbox
MCP support
Exposes inbox and email operations as tools to MCP clients such as Claude and Cursor. Read-only and sending tools have annotations that support client confirmation behavior.
Configuration
Remote servers need no local install. Pick your client, then copy the config or install in one click.
https://api.send0.dev/mcpclaude mcp add --transport http send0-dev-send0 https://api.send0.dev/mcp{"mcpServers":{"send0-dev-send0":{"type":"http","url":"https://api.send0.dev/mcp"}}}Open in Cursor{"servers":{"send0-dev-send0":{"type":"http","url":"https://api.send0.dev/mcp"}}}Open in VS Code{"mcpServers":{"send0-dev-send0":{"type":"http","url":"https://api.send0.dev/mcp"}}}{"mcpServers":{"send0-dev-send0":{"serverUrl":"https://api.send0.dev/mcp"}}}Run commands in a terminal; paste JSON into the client’s MCP config and restart. Servers that need sign-in will prompt on first connect.
https://api.send0.dev/mcpAuth requiredTools
Details
From the project README@send0/mcp
MCP server for send0. Give Claude, Cursor or any MCP client its own email inbox: sign up for things, read verification codes, and hold real email conversations.
Tools
| Tool | What it does |
|---|---|
create_inbox | Make a new address, e.g. [email protected] |
list_inboxes | Inboxes this key can use |
wait_for_email | Block until a matching email arrives; returns the one-time code and verify link already extracted |
search_messages | Full-text search, filter by sender (*@github.com) or direction |
get_message | Read one message (new text only by default, to save tokens) |
list_threads / get_thread | Read whole conversations, oldest first |
send_email | Start a new thread |
reply | Answer in the same thread |
Email bodies are returned inside <untrusted_email> tags with a note to treat them as data, and messages flagged for prompt injection carry a visible warning. Read-only tools are annotated readOnlyHint, and sending tools openWorldHint, so clients can ask before sending.
Setup
Get an API key at https://send0.dev. A key limited to one inbox is the safest choice for an agent.
Claude Code
claude mcp add send0 --env SEND0_API_KEY=s0_live_… -- npx -y @send0/mcp
Claude Desktop / Cursor
{
"mcpServers": {
"send0": {
"command": "npx",
"args": ["-y", "@send0/mcp"],
"env": { "SEND0_API_KEY": "s0_live_…" }
}
}
}
Options
| Variable | |
|---|---|
SEND0_API_KEY | Required |
SEND0_INBOX_ID | Default inbox, so tools don't need inbox_id |
SEND0_BASE_URL | For self-hosted send0 |
Use it from code
import { createSend0Server } from "@send0/mcp";
import { Send0 } from "@send0/sdk";
const server = createSend0Server({ client: new Send0(process.env.SEND0_API_KEY) });
// connect any MCP transport
License
MIT
Comments
New to MCP?
From what the protocol is to installing your first server, these answers cover most first questions.
An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.