MailFlat MCP server

Read from the package source without running it. The installed server may list more.

• burn_inboxwrite action

  Delete every message in an inbox but KEEP the address.

• create_inboxwrite action

  Open an email inbox and return its address. Use this when you need an address to sign up for a service or to receive a one-time code.

• delete_inboxwrite action

  Delete an inbox and all its messages by address. Irreversible.

• delete_messagewrite action

  Delete a single message in an inbox by its id (the inbox itself stays).

• list_inboxes

  List all inboxes available to this API key.

• mark_read

  Mark one message as read so later polls can skip it.

• read_messages

  Read messages in the given inbox address (newest first).

• reply

  Reply to a message so it stays in the SAME conversation.

• send_emailwrite action

  Send an email FROM the given inbox address (DKIM-signed via MailFlat's MTA). Use for replies or outbound automation. `html` is optional.

• wait_for_message

  Poll the inbox until a new message ARRIVES (or timeout). Returns {email}.

• wait_for_otp

  Poll the inbox until an OTP code arrives (or timeout). Returns {otp_code, email}.

• wait_until_sent

  Find out whether a mail you sent was actually delivered.

• Code scan5 source files scanned25/25
• –Live reliabilityno gateway calls yet and no remote to proben/a
• –Tool poisoningtools not inspected (local package is not executed); not countedn/a
• Auth qualitystatic API keys via environment variables6/15
• Maintenancelast push 28 days ago15/15
• Maintainer identityregistry namespace matches repository owner6/10

MailFlat: common questions

Is MailFlat MCP server safe?

Mostly: it is graded B (80/100). Read the MailFlat safety report

How do I install MailFlat?

It runs on your machine. Copy the Claude Code, Claude Desktop or Cursor config from the install section.

Does MailFlat need an API key?

Yes. The registry entry asks for MAILFLAT_API_KEY.

Is MailFlat maintained?

The last commit was 28 days ago (2026-08-23). The latest release is v0.9.2.

What can I use instead of MailFlat?

Servers from other publishers that do the same job: Agent Email MCP server, EmptyInbox MCP server and Postfleet MCP server. Compare all MailFlat alternatives.