inbox-rotation-scalinglisted

# Inbox Rotation and Scaling There's one rule for scaling cold email volume: **add mailboxes, never raise per-mailbox volume.** A mailbox has a safe ceiling of roughly 150 emails a day at full warmup. That number comes from what a busy human plausibly sends, and exceeding it is the pattern providers are built to detect. Capacity comes from having more mailboxes at safe volume, not from pushing any one of them harder. ## The maths ``` Target: 1,000 cold emails per day 1,000 ÷ 150 per mailbox = 7 mailboxes minimum 7 mailboxes ÷ 3 per domain = 3 domains Realistically: 4 domains × 3 mailboxes = 12 mailboxes 12 × 120/day (below ceiling) = 1,440/day capacity Run at ~70% for headroom = ~1,000/day ``` Always build in headroom. Running every mailbox at its maximum leaves no room for a warmup pause, a mailbox going unhealthy, or a volume spike, and it means any incident immediately becomes a capacity problem. ## Two to three mailboxes per domain More concentrates risk. If a domain gets flagged, every mailbox on it goes down together, so spreading across domains is what limits the blast radius. ``` outbound-a.com sarah@ , tom@ , priya@ outbound-b.com sarah@ , tom@ , priya@ outbound-c.com sarah@ , tom@ , priya@ ``` Use real names of real people who work there. `sales@`, `outreach@` and `noreply@` are recognisable as bulk-sending addresses and they're also harder for a recipient to answer, because nobody replies to a role account. Each