Why new mailboxes need a ramp-up
Mailbox providers judge a sender by history. A brand-new inbox that suddenly sends hundreds of cold emails looks exactly like a compromised account, so filters respond by routing mail to spam or throttling it entirely.
Warmup builds that history deliberately: small volumes, real engagement and a steady upward curve that tells Google and Microsoft this sender behaves like a person.
A safe three-week ramp
Week one: 5–10 warmup emails per day, no cold outreach. Week two: 15–25 per day, with a handful of low-risk campaign sends to your warmest segment. Week three: ramp to your target cap — usually 30–40 per mailbox — while keeping warmup running in the background.
CloudJet automates this curve per mailbox and pauses the ramp if bounce or complaint rates move in the wrong direction.
Signals worth watching
Bounce rate should stay under 2%, spam complaints under 0.1%, and seed placement in the primary tab above 90%. If any of these slip, hold volume flat for a few days rather than pushing through.
Deliverability is a habit, not a setting. Automate the guardrails, watch the signals, and scale only as fast as your reputation allows.