TL;DR: Treat every contact-form notification as an auditable state machine, not a successful API call. Verify a DKIM-aligned sending domain, consult a regional suppression set before enqueueing, assign an idempotency key, and poll the delivery interface until each attempt reaches a terminal state. For a healthtech support router, that evidence is what separates "accepted" from "handled." The storage bill is driven less by the contact form itself than by retained delivery evidence: status snap...