Credits
One credit, one recipient
Every HTTP and SMTP send holds credits, injects to Kumo, then commits — or voids on failure. No silent overdraft.
Ledger
Hold → commit → void
Idempotency key unique per workspace. FOR UPDATE on the wallet row.
Hold
Reserve amount = billable recipients before inject.
Inject
Kumo /api/inject/v1 from panel, /v1/send, or SMTP AUTH.
Commit or void
Debit on success; void restores the hold on failure.
Top-up
Air-gap default vs Stripe optional
Operator reference: credits & prepaid hold· send flow
- ComplianceSOC 2-aligned
- DeploymentManaged appliance · On your VPC
- Statushosted.postmta.com/status
- IncidentsNo open incidents