Every SaaS Tenant Needs Its Own Email Kill Switch
PostShiba fits drovr's SendPort seam: per-tenant isolation, a sending kill switch, delivery diagnostics, and a role-scoped MCP ops surface.
PostShiba exposes the email infrastructure behind Bento as a platform for products that send on behalf of their customers. The useful abstraction isn’t another send API. Each tenant gets separate domains, SMTP credentials, inboxes, and suppressions. An operator can suspend one tenant while everyone else keeps sending. The email layer owns the blast-radius control.
That makes PostShiba a plausible SendPort adapter for drovr. It can answer delivery questions through analytics grouped by mailbox provider, recipient history, message events, and sending status. It can also receive mail through hosted or custom inboxes and emit signed webhooks. The AI agent inbox guide gets the boundary right: verify, store, enqueue, treat email as untrusted input, and require approval before sending a reply.
The Model Context Protocol surface is not a second automation system bolted beside the API. Every MCP tool maps to a documented REST endpoint, with the same payment, identity, and sending gates. Full keys can send, rotate credentials, and pause tenants; Support keys expose only five read-and-repair tools and cannot reconfigure the account. That’s the clever bit: agent-native operations inherit the existing permission model instead of creating a new back door. The catch is real: access is invite-only during beta, and production sending requires a separate review. This is an adapter candidate to test, not a production default to assume.
Key Ideas
- Multi-tenant isolation scopes sending domains, SMTP credentials, inboxes, and suppressions to one customer namespace.
- The MCP operations surface can suspend or resume one tenant without stopping the rest of the platform.
- Mailbox-provider analytics, recipient lookup, message events, and status checks make delivery diagnosis part of the platform API.
- A Support key exposes
whoami,lookup_recipient,get_analytics,get_status, anddestroy_suppression, while withholding sending, account reconfiguration, credentials, secrets, and raw bounce payloads. - Inbound inboxes plus signed webhooks provide the primitives for support desks and agent mailboxes without mixing message ingestion with model execution.
- Invitation and production approval are separate gates; beta access does not authorize live outbound mail.