Atomic Mail — Claude Code MCP server: features and setup
Atomic Mail connects an AI agent to an inbox for reading, sending, searching, and drafting email. Use it to handle mailbox tasks from Claude Code.
claude mcp add --transport http mcp https://mcp.atomicmail.ai/mcpWhat Atomic Mail does
Atomic Mail gives an agent an inbox and access to email operations through JMAP, including reading and sending messages, managing drafts and threads, and searching. Its MCP integration exposes register, jmap_request, and help; connect it over HTTP or run it with stdio.
Inbox signup uses proof of work and does not require CAPTCHA or manual approval. In Claude Code, add the HTTP server with the command below and restart the host. The stdio option needs values for ATOMIC_MAIL_CREDENTIALS_DIR, ATOMIC_MAIL_API_KEY, ATOMIC_MAIL_AUTH_URL, ATOMIC_MAIL_API_URL, and ATOMIC_MAIL_INBOX_DOMAIN, so you’ll need those before configuring that route.
What it helps with
- create an inbox for an AI agent
- read email through JMAP
- search a mailbox for a specific thread
- prepare an email draft
- send a message from an agent
Example prompts for the agent
- Create an Atomic Mail inbox for me.
- Find the email thread about the approval and summarize it.
- Draft a reply to the latest message from the client.
How to install Atomic Mail
1Platform CLI: remote server
claude mcp add --transport http mcp https://mcp.atomicmail.ai/mcp2Platform CLI
claude mcp add --env ATOMIC_MAIL_CREDENTIALS_DIR=<ATOMIC_MAIL_CREDENTIALS_DIR> --env ATOMIC_MAIL_API_KEY=<ATOMIC_MAIL_API_KEY> --env ATOMIC_MAIL_AUTH_URL=<ATOMIC_MAIL_AUTH_URL> --env ATOMIC_MAIL_API_URL=<ATOMIC_MAIL_API_URL> --env ATOMIC_MAIL_INBOX_DOMAIN=<ATOMIC_MAIL_INBOX_DOMAIN> --transport stdio atomic-mail -- npx -y @atomicmail/mcp-modelcontextprotocolReplace <…> with your own values
1Platform CLI: remote server
codex mcp add atomic-mail --url https://mcp.atomicmail.ai/mcp2Platform CLI
codex mcp add atomic-mail --env ATOMIC_MAIL_CREDENTIALS_DIR=<ATOMIC_MAIL_CREDENTIALS_DIR> --env ATOMIC_MAIL_API_KEY=<ATOMIC_MAIL_API_KEY> --env ATOMIC_MAIL_AUTH_URL=<ATOMIC_MAIL_AUTH_URL> --env ATOMIC_MAIL_API_URL=<ATOMIC_MAIL_API_URL> --env ATOMIC_MAIL_INBOX_DOMAIN=<ATOMIC_MAIL_INBOX_DOMAIN> -- npx -y @atomicmail/mcp-modelcontextprotocolReplace <…> with your own values
Config file
{
"mcpServers": {
"atomic-mail": {
"url": "https://mcp.atomicmail.ai/mcp"
}
}
}{
"mcpServers": {
"atomic-mail": {
"command": "npx",
"args": [
"-y",
"@atomicmail/mcp-modelcontextprotocol"
],
"env": {
"ATOMIC_MAIL_CREDENTIALS_DIR": "<ATOMIC_MAIL_CREDENTIALS_DIR>",
"ATOMIC_MAIL_API_KEY": "<ATOMIC_MAIL_API_KEY>",
"ATOMIC_MAIL_AUTH_URL": "<ATOMIC_MAIL_AUTH_URL>",
"ATOMIC_MAIL_API_URL": "<ATOMIC_MAIL_API_URL>",
"ATOMIC_MAIL_INBOX_DOMAIN": "<ATOMIC_MAIL_INBOX_DOMAIN>"
}
}
}
}Replace <…> with your own values
Config file
{
"servers": {
"atomic-mail": {
"type": "http",
"url": "https://mcp.atomicmail.ai/mcp"
}
}
}{
"servers": {
"atomic-mail": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@atomicmail/mcp-modelcontextprotocol"
],
"env": {
"ATOMIC_MAIL_CREDENTIALS_DIR": "<ATOMIC_MAIL_CREDENTIALS_DIR>",
"ATOMIC_MAIL_API_KEY": "<ATOMIC_MAIL_API_KEY>",
"ATOMIC_MAIL_AUTH_URL": "<ATOMIC_MAIL_AUTH_URL>",
"ATOMIC_MAIL_API_URL": "<ATOMIC_MAIL_API_URL>",
"ATOMIC_MAIL_INBOX_DOMAIN": "<ATOMIC_MAIL_INBOX_DOMAIN>"
}
}
}
}Replace <…> with your own values
1Platform CLI: remote server
gemini mcp add -t http atomic-mail https://mcp.atomicmail.ai/mcp2Platform CLI
gemini mcp add -e ATOMIC_MAIL_CREDENTIALS_DIR=<ATOMIC_MAIL_CREDENTIALS_DIR> -e ATOMIC_MAIL_API_KEY=<ATOMIC_MAIL_API_KEY> -e ATOMIC_MAIL_AUTH_URL=<ATOMIC_MAIL_AUTH_URL> -e ATOMIC_MAIL_API_URL=<ATOMIC_MAIL_API_URL> -e ATOMIC_MAIL_INBOX_DOMAIN=<ATOMIC_MAIL_INBOX_DOMAIN> atomic-mail npx -y @atomicmail/mcp-modelcontextprotocolReplace <…> with your own values
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Atomic Mail
How do I install Atomic Mail in Claude Code?
Add the HTTP server with claude mcp add --transport http mcp https://mcp.atomicmail.ai/mcp, then restart Claude Code.
What does Atomic Mail do?
It connects an agent to an email inbox through MCP. The agent can register an inbox and perform mailbox operations using JMAP.
Do I need credentials to connect Atomic Mail?
The Claude Code HTTP setup uses the MCP server URL. The stdio setup requires values for ATOMIC_MAIL_CREDENTIALS_DIR, ATOMIC_MAIL_API_KEY, ATOMIC_MAIL_AUTH_URL, ATOMIC_MAIL_API_URL, and ATOMIC_MAIL_INBOX_DOMAIN.
