How many email domains should one application be allowed to manage? Most email platforms answer with a number and a pricing tier. Nylas Agent Accounts — programmatic mailboxes currently in beta — answer with: unlimited. One application can host agent mailboxes across any number of registered domains, and that single design decision shapes how you organize tenants, environments, and brands.
Here's how multi-domain setups actually work, and the three patterns the provisioning docs call out.
Domains are the unit of identity
Every agent mailbox lives on a domain. Before creating an account, you register the domain once per organization — then create as many accounts under it as your plan allows. Registration takes three steps: add the domain in the Dashboard (picking the US or EU data center region), publish the generated DNS records at your provider, and wait for automatic verification. Two record types do the work: an MX record routes inbound mail, and TXT records prove ownership and set up SPF/DKIM for outbound.
Once a domain's status hits verified, account creation is one call:
