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