$ man ramp-to-sixty

Raise to 60

The warmup target where a mailbox's daily sending volume (warmup + campaign combined) reaches approximately 60 emails per day. This is the point where the mailbox has enough reputation data to send reliably at its campaign-level limits (25-30/day for Google, 10-20/day for Microsoft) while warmup continues in the background.

Warmup doesn't stop when campaigns start. Even during active sending, the warmup pool continues running to maintain engagement metrics. The "raise to 60" target means the mailbox handles ~30 warmup emails + ~30 campaign emails (for Google). This blended volume keeps the mailbox's engagement rate healthy because warmup emails always get opened and replied to. It's a counterweight to the cold campaign emails that may not get engagement.

In Instantly's warmup settings, I set the ramp-up target to 60 per day. As the mailbox warms, Instantly gradually increases warmup volume. Once it hits 60 and I start campaigns, the split is roughly 50/50 warmup/campaign. Over time, as the mailbox builds campaign-level reputation, I can shift the ratio — more campaign, less warmup. But I never fully disable warmup on an active sending mailbox. The warmup pool is the safety net.