<b>Inbox rotation: the setting that saves your main domain</b>

<b>Inbox rotation: the setting that saves your main domain</b>
The single biggest deliverability lever isn't a tool feature — it's how you spread load across it.

Never send cold from your primary domain. Buy 2-3 lookalike domains (yourco.io, getyourco.com), put 2-3 inboxes on each, and rotate. Smartlead and Instantly both auto-distribute a campaign across all connected inboxes so no single mailbox exceeds ~30-50 sends/day.

Pros / Cons
— Multi-domain rotation: protects your brand domain, contains blacklist damage
— More inboxes: better spread, higher Google Workspace seat cost (~$6/inbox/mo)
— Cheap throwaway domains: fast, slightly weaker initial reputation

Who it's for: anyone sending more than 50 cold emails/day. Below that, one warmed inbox is fine.

Verdict: 5/5 — rotation is mandatory infrastructure, not optimization. Both Smartlead and Instantly do it well; the skill is buying and aging the domains 2-3 weeks before you fire. Skip the aging and rotation won't save you.