MCP quickstart

The send0 MCP server gives your assistant tools to create inboxes, wait for email, read threads and reply.

Give the assistant an API key limited to what it needs. A key with read and send scopes, restricted to one inbox, is the safest choice. See API keys.

Connect

There are two ways to run it. They have the same tools.

Remote, nothing to install: point your client at https://api.send0.dev/mcp and send your API key as a Bearer token.
Local, over stdio: run npx @send0/mcp on your machine. Use this for clients that only support local servers.

Self-hosting send0? Both work: use https://<your domain>/mcp for remote, or set SEND0_BASE_URL for local. See Self-hosting.

Remote

claude mcp add --transport http send0 https://api.send0.dev/mcp \
  --header "Authorization: Bearer s0_live_…"

Add ?inbox_id=ibx_… to the URL if the assistant should always use one inbox. The tools then don't need an inbox_id.

Local

claude mcp add send0 --env SEND0_API_KEY=s0_live_… -- npx -y @send0/mcp

Set SEND0_INBOX_ID=ibx_… as well if the assistant should always use one inbox.

Try it

Ask your assistant:

Create a send0 inbox called demo. I'll email it from my own address. Wait for that email and summarize it, then reply saying thanks.

It will call create_inbox, then wait_for_email, then reply. Email the address from your own mailbox while it waits.

What the assistant sees

Message bodies come back wrapped as untrusted data, with the useful parts first:

id: msg_9Kd2  thread: thr_3Lp8  direction: in  status: received
from: Acme <noreply@acme.dev>
subject: Your Acme verification code
one-time code: 482913
action link: https://acme.dev/verify?token=…
sender auth: SPF pass, DKIM pass, DMARC pass
<untrusted_email id="msg_9Kd2">
Enter this code to verify your email address: 482913
</untrusted_email>

Emails flagged for prompt injection carry a visible warning. See Prompt-injection safety and the full tool list.

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