Warmup is about gradually building sender reputation. Most tools automate this, but the principles matter.
Start with 10-20 sends per day. Scale by 10-20% daily. Get replies from real humans (use a warmup pool). Don’t skip days. Don’t accelerate too fast.
A properly warmed domain can send 30-50 cold emails/day reliably. Push beyond that and you’ll see deliverability degrade.