Your domain gets a background check
Three DNS records decide whether you're a sender or a suspect. Bucktooth checks SPF, DKIM and DMARC live, and a domain that flunks its own paperwork doesn't get to send. Not "gets a warning." Doesn't send.
Every domain keeps its own warm-up schedule, its own daily ceiling, and its own reputation history — so if one ever goes sideways, it retires alone instead of taking the rest down with it.