If I were to be honest, skipping warm-up is the fastest way to land in spam.
Even domains with good sender reputation need a warm-up phase when increasing volume or starting cold outreach — mailbox providers see a sudden spike as suspicious.
1. If the domain is brand-new
- Minimum: 3–4 weeks of gradual warm-up.
- Start at 10–15 emails/day (realistic, human-like sending) and increase slowly.
- Use a mix of replies, forwards, and genuine interactions, not just one-way sends.
2. If the domain has been dormant
- Minimum: 2 weeks.
- Reactivate with low-volume, engaged sends before any campaigns.
3. If the domain is active & has a good reputation
- Warm-up may be as short as 5–7 days when starting a new sequence, but still ramp up volume gradually.