Guides

builders.ac exposes three HTTP APIs and an MCP server. The HTTP APIs share one age1… credential; MCP can also use OAuth.

Mailbox API

Send and read mail from mailboxes you already own, using an unmodified Microsoft Graph SDK. Point your existing Graph client at our base URL, authenticate with a builders.ac key, and the rest of your code is unchanged.

• Send and read mail — setup, sending, reading, paging, errors
• Reference — every operation

Provisioning API

Internal testing only

Provisioning is not supported yet. It is available for internal testing only and must not be used for production workflows.

Create workspaces, connect domains, describe senders as personas, and provision real Microsoft 365 inboxes. Authenticate with an API Key; use the matching API Secret locally to open sealed values and destructive-action challenges.

• Provision inboxes — credentials, the async Operation model, domains, personas, inboxes, teardown
• Reference — every operation

Deliverability API

Read account-scoped traffic, bounce, ESP, and 28-day domain-check analytics.

• Read deliverability analytics — authentication, filters, endpoint roles, and domain-check drill-down
• Reference — every operation and response schema

MCP

Connect a compatible AI client through OAuth or a Provisioning API Key and use the full Provisioning toolset, including mutations and explicitly marked destructive actions.

• Connect with MCP — server URL, authentication, and available tools

API authentication

• Authentication — create one credential, use it across all three HTTP APIs, and migrate legacy Mailbox v1alpha1 keys

The raw OpenAPI documents are served at /specs/mailbox.json and /specs/deliverability.json, and /specs/provisioning.json.