How many cold emails can you send per inbox per day?

Keep it to roughly 30–40 emails per inbox per day on a warmed mailbox. Pushing a single inbox harder is the fastest way to damage its sender reputation and start landing in spam.

To send more, add inboxes and domains in rotation rather than raising the per-inbox limit. New mailboxes should start much lower — around 5–10 a day — and ramp over two to three weeks before reaching full volume.