Scaling to Thousands of Agent Mailboxes

Week one: a single test mailbox on a trial domain, provisioned by hand from the dashboard. Week twelve: a fleet of agent mailboxes spread across customer domains, each sending real mail with its own quota and reputation. The API calls are the same at both scales — what changes is everything around them: how you provision, how you share configuration, and how you keep one bad sender from pausing the fleet. Here's what the path from one to thousands looks like with Nylas Agent Accounts , which are currently in beta. Provisioning is a loop, not a ceremony There's no OAuth dance to scale around. Creating a mailbox is one POST with "provider": "nylas" — no refresh token, no consent screen — so a fleet provisioner is just iteration: curl --request POST \ --url "https://api.us.nylas.com/v3/connect/custom" \ --header "Authorization: Bearer <NYLAS_API_KEY>" \ --header "Content-Type: application/json" \ --data '{ "provider": "nylas", "workspace_id": "<WORKSPACE_ID>", "settings": { "email": "agent-0042@agents.yourcompany.com" } }' Two scaling-relevant details in that request. First, the domain: one application can manage accounts across any number of registered domains, and the docs explicitly recommend splitting high-volume outbound across multiple domains ( sales-a.yourcompany.com , sales-b.yourcompany.com ) so reputation damage on one doesn't contaminate the rest. Second, the workspace_id : passing it at creation is how each account picks up its configuration, which brings us to the part that makes fleets manageable. Configure workspaces, not grants At fleet scale, per-grant configuration is a non-starter. The model here is indirection: policies and rules attach to workspaces , and every account in a workspace inherits them. One policy object — daily send quota, storage cap, retention windows, spam sensitivity — governs a thousand mailboxes, and updating it updates all of them at once. The recommended carve-up is one workspace per agent archetype: outreach agents get a work