Postfleet

Postfleet is an email infrastructure solution designed specifically for AI agents. It addresses the critical security vulnerabilities that arise when AI agents are given direct access to email inboxes. The primary purpose of Postfleet is to act as a secure intermediary, ensuring that all incoming and outgoing email communications are safe, reliable, and properly processed before interacting with an AI agent. AI agents are increasingly being integrated into workflows that involve email communication. However, raw email inboxes present a significant attack surface. Threats such as prompt injection, where malicious instructions are embedded within emails to manipulate the agent's behavior, alongside traditional spam and viruses, pose substantial risks. Without proper safeguards, these vulnerabilities can lead to compromised agent performance, data breaches, and unintended actions. Postfleet was developed to mitigate these risks by providing a robust security layer for agent-based email interactions. One of the core features of Postfleet is its inbound message verification and screening. Every incoming email undergoes rigorous checks, including SPF, DKIM, and DMARC authentication, to ensure sender legitimacy. It also screens messages for spam and viruses, preventing malicious content from reaching the agent. Crucially, Postfleet employs advanced techniques to detect and neutralize prompt injection attempts, safeguarding the agent from manipulation. Another key capability is the parsed and comprehended delivery of inbound messages. Instead of presenting raw email text to the agent, Postfleet processes the content and delivers it as structured JSON, parsed according to a predefined schema. This ensures that the agent receives clean, organized data, eliminating the need for the agent to parse unstructured email content and reducing the risk of misinterpretation or errors. For outbound communications, Postfleet offers idempotent sending, which prevents accidental duplicate emails from being sent. It also includes an optional human approval step, allowing for a final review before an agent-generated email is dispatched. This feature adds an extra layer of control and accountability, particularly important for sensitive or high-stakes communications. Postfleet provides multiple ways for agents to interact with its services. It offers 6 MCP (Message Control Protocol) tools, designed for seamless integration into existing agent setups. Additionally, a comprehensive REST API is available for developers who need more programmatic control over email handling and agent communication workflows. The overall methodology of Postfleet is to treat the email inbox as a hostile environment by default. It acts as a security gateway, filtering and sanitizing all communications before they reach the AI agent. This proactive approach ensures that agents can safely leverage email as an input channel without being exposed to the inherent risks of direct inbox access. The benefits of using Postfleet include enhanced security for AI agents, preventing prompt injection and other cyber threats. It also improves agent reliability by providing clean, structured data, reducing errors and misinterpretations. The idempotent outbound sending and optional human approval ensure controlled and safe outgoing communications, minimizing risks associated with automated email. Postfleet can be used in various scenarios. For instance, an AI customer service agent can safely receive and process customer inquiries without the risk of prompt injection. An AI assistant managing internal communications can handle requests and notifications securely. Automated workflows that require agents to respond to emails can do so with confidence, knowing that the communication channel is protected. Postfleet is available with a free tier and does not require a credit card for signup. It is designed for developers and teams building AI agents that require email integration. The product is accessible via its web interface and REST API, with MCP tools available for easier integration. Specific details on the tech stack are not explicitly mentioned, but it is built with security and developer tooling in mind. In summary, Postfleet offers essential email infrastructure for AI agents, providing robust security, reliable data processing, and controlled outbound communications to enable safe and effective agent-based email interactions.