Build a vendor onboarding agent with its own email inbox

Vendor onboarding usually starts with one clean request and then turns into a messy thread. Procurement asks for a W-9, security asks for a SOC 2 report, finance asks for remittance details, legal asks for an executed agreement, and the vendor replies with four attachments across three messages because different people own different parts of the process. That is exactly the kind of workflow where a generic "AI email assistant" gets risky. You do not want a model improvising legal language, requesting bank details in the wrong channel, or forwarding a confidential report to the wrong internal alias. You want the agent to own the repetitive coordination while your application keeps the state machine, policy, audit log, and approvals. The pattern I reach for is a dedicated Nylas Agent Account: vendors@yourcompany.com . It is a real mailbox the onboarding agent owns. It receives the vendor's replies, detects what is attached, updates your vendor record, sends safe reminders, and escalates missing or sensitive items to a human. The agent is not borrowing an employee's inbox, and it is not scraping a shared procurement mailbox. It has a grant, an email address, webhooks, threads, folders, and the same Messages API you would use for any other mailbox. I work on the Nylas CLI, so the terminal examples below use the commands I would use while building and debugging this flow. I also include the raw API calls because the production version belongs in your service, not in a shell script. What the agent should own Start by drawing the boundary tightly. A vendor onboarding agent should own message handling and coordination, not business approval. Good responsibilities: Receive vendor replies at a stable address. Read message bodies and attachment metadata. Match a reply to an existing vendor record. Detect which onboarding items are complete, missing, expired, or unreadable. Draft reminders and status updates. Schedule handoff calls when the vendor asks for help. Escalate sensit