A domain with perfect DNS records is still useless if the mailboxes sending from it have no sending history. Warmup is the process of building that history gradually and safely, and it is the step most cold email setups skip or rush, which is why so many campaigns burn out in the first two weeks.
Mailbox Setup
We provision mailboxes across Google Workspace and Microsoft 365, typically splitting roughly 60% Google Workspace and 40% Microsoft 365 across your domain estate. This mixed-provider approach means that if one provider network flags unusual activity, it does not take down every mailbox you own at once. Daily sending limits are capped at 30 to 50 emails per mailbox from day one, a limit that stays in place permanently, not just during warmup.
The Warmup Ramp
- Week 1: mailboxes send and receive automated warmup emails only, no real campaign traffic, building initial sender history
- Week 2: warmup volume increases while low-volume, closely monitored real sending can begin in parallel
- Week 3: volume continues ramping as inbox placement and engagement metrics are checked daily
- Week 4: full campaign volume unlocked once sender reputation scores and placement tests are consistently clean
Tools We Run Warmup Through
Warmup is executed and monitored through dedicated warmup networks including Mailreach, Warmy.io, and Lemwarm, which simulate real inbox engagement, opens, replies, and moving mail out of spam, at a pace that mirrors organic usage rather than an obvious bot pattern.
What Happens If You Skip This Step
Mailboxes that go straight to full-volume sending with no warmup history are the single most common cause of a campaign getting flagged inside the first 72 hours. Providers like Google and Microsoft actively watch for exactly this pattern: a brand new mailbox suddenly sending hundreds of near-identical emails.