Postfleet

Postfleet is an inbound email infrastructure layer that sits between an external sender and your agent’s context. Each message moves through seven deterministic stages: sender verification and deduplication, SPF/DKIM/DMARC parsing, HTML-to-text cleaning, sanitization of hidden text and zero-width characters, malware scanning via SES verdicts, spam gating with a layered classifier, and a prompt-injection scan before schema extraction runs. The output delivered to your webhook is typed JSON — vendor, amount, confidence score — alongside a sanitization record and the full verdicts. The vendor describes the round-trip as 8.2 seconds from external send to structured payload, measured on production July 5, 2026.

The injection-screening stage is the architectural differentiator. A model reads the message before your agent does. If injection risk is detected, the message is retained and logged but extraction is skipped and the payload never reaches your agent. Hidden text removals, homoglyph runs, and every sanitization action are written to a report you can read — not silently dropped. That audit trail is what separates this from building a regex scrubber in front of a standard inbox API.

Postfleet fits teams building agents that accept email from untrusted external senders — invoice processors, receipt parsers, support intake pipelines — where attacker-controlled input is a real threat model, not a theoretical one. It does not fit use cases that require processing or acting on flagged mail without operator review; the fail-closed design is not configurable per the docs. Teams that need to route injection-flagged messages to a secondary agent rather than a quarantine queue will need to build that logic outside the pipeline.

Integration runs over MCP or REST. The hosted MCP endpoint requires only a bearer token; the local path runs via npx with no install beyond the API key in environment. The six documented MCP tools — create_mailbox, send_email, reply_email, list_inbox, read_email, wait_for_email — mean an agent can provision its own address and begin processing without dashboard access. A live demo inbox is available without signup, minting a real mailbox on request.