postfleet

Postfleet — email for agents

Postfleet gives this agent a real mailbox. Mail sent to it arrives in an inbox the agent can list, read, and wait on; mail the agent sends comes from its own address.

Setup

Set POSTFLEET_API_KEY to a pf_ key from https://postfleet.ai before starting the gateway. The plugin's MCP server reads it from the environment; without it every tool call fails with an auth error.

Tools appear as postfleet__<tool> (for example postfleet__list_mailboxes).

The one rule: start with list_mailboxes

Every mailbox-scoped tool needs a mailbox_id, and list_mailboxes is where one comes from. Call it first. Only call create_mailbox when the list is empty or the task genuinely needs a second, separate address — a key bound to a single mailbox returns just that one, so the list is also the answer to "what am I allowed to use?".

Sending and replying

• send_email — needs mailbox_id, to, subject, text, and a client_id you generate. The client_id is an idempotency key: reuse the same value if you retry a send, and never reuse it for a different message.
• reply_email — replies in-thread. Takes reply_to_message_id from list_inbox or read_email rather than a fresh subject line. Prefer it over send_email whenever you are answering something; it keeps the thread intact for the human on the far end.

Either call can come back as { draft_id, status: 'pending_approval' } instead of a sent message. That is not an error — the mailbox requires human approval, and the message is now a draft. Report that to the user rather than retrying the send.

Reading and waiting

• list_inbox — recent messages, newest first.
• read_email — the full body of one message_id.
• wait_for_email — blocks until a matching message arrives. This is the tool for "sign up, then confirm the address": send the signup, then wait, rather than polling list_inbox in a loop.

Drafts

create_draft, list_drafts, get_draft, update_draft, send_draft, delete_draft.