$ man pulling-domains

Pulling a Domain Without Killing a Campaign

The ability to remove a domain from active sending — due to reputation issues, bounce spikes, or spam reports — without disrupting the overall campaign. Requires redundancy and rotation infrastructure.

If a domain gets flagged by Gmail or Microsoft, continuing to send from it tanks deliverability for every email from that domain. You need to pull it immediately. But if pulling a domain means losing 1/18th of your sending capacity with no backup, the campaign slows down. Having pre-warmed backup mailboxes on standby means pulling a domain is a swap, not a loss.

When I see deliverability metrics drop for a specific domain (open rates cratering, bounce rates spiking, spam complaints increasing), I pull that domain from the active campaign in Instantly. The backup mailbox on that domain stays in warming mode. I swap in a backup mailbox from a different domain that's been warming passively. The campaign continues at full volume. The flagged domain rests for 2-4 weeks. If it recovers, it re-enters rotation. If it doesn't, I retire it and provision a replacement.