A team ships their first email agent on a Thursday. Demo went great, handler's deployed, webhook's registered. Friday morning the on-call wakes up to an inbox where the agent has been enthusiastically replying to its own replies all night, a customer who received the same answer three times, and a thread in Gmail that's shattered into five separate conversations. None of it was an exotic failure — every one of these is a known pitfall with a known fix, documented in the Nylas Agent Accounts cookbook (the product's in beta; the mistakes are timeless).
Here are the nine I'd check before any launch.
1. The agent replies to itself
The message.created webhook fires for outbound messages too — when your agent sends a reply via the API, that sent message triggers the same event as inbound mail. Skip this check and you've built a perpetual motion machine: reply, webhook, reply.
Fix: filter the agent's own address at the very top of the handler, before any other logic.
