Are you guys sending cold emails?

Yes, hire a professional.

Google Postmaster Tools, it's free and it's the only real signal for Gmail. Verify each sending domain, watch spam rate. Above 0.3% you're cooked. Blacklist checks (MXToolbox) lag too much to be useful, by the time you're listed you've been burning for weeks. But stop watching opens, Apple MPP made them meaningless. Watch reply rate. Same list, same copy, replies drop 30% week over week? That's your domain dying, and it shows weeks before any blacklist. At 3k/day though, you're not keeping domains alive, you're churning them. The question isn't "is this burnt", it's "what does a domain cost to replace and is my close rate covering the burn"

The domain replacement cost point above is the real economics of this, and the lever most people ignore on that math is spam complaint rate, since that is what actually drives the burn clock, not raw send volume by itself. A generic template sent 3000 times a day generates a lot more complaints per send than something that references a real detail about the recipient, even at a fraction of the volume. I moved away from high volume generic sends for that exact reason, doing real research per prospect and writing the email around something specific to that business instead of a template. It caps how many I can send in a day, but the complaint rate stays low enough that domain replacement is a rare cost instead of a constant one. At 3000 a day the math might still favor your current approach if your close rate covers the churn, but it is worth checking whether the complaint rate itself, not just the volume, is what is actually burning the domains faster than expected.

Depends on how many mailboxes/domains you're using for your 3K figures