How to prevent duplicate emails when AI agents retry sends after timeouts

An AI agent may send an email that the service accepts, yet lose the connection before receiving confirmation, so a naive retry could deliver the same message twice. Because a timed-out request leaves the outcome unknown, simply trying again is risky. The article recommends creating and saving an idempotency key before the first attempt, so that retries are recognized as the same action. It also advises storing campaign details, message content, key, state, and email ID in a database, and marking uncertain operations as unknown rather than returning them to the unsent queue. Using Hail MCP as an example, it shows how to check a message's status with its email ID and to wait and investigate when a request is still processing.