Sending capacity planner
The arithmetic that decides whether your domain survives the quarter.
Twenty to thirty is a defensible ceiling for a warmed mailbox.
Read this before trusting the number
Capacity is arithmetic; deliverability is not. This tells you how many mailboxes it takes to reach a volume without any single one looking abnormal. It cannot tell you whether the messages deserve to arrive, and that is the larger half of the problem.
Start with one task
The whole working product is free. Reports and the extension are $5 a month, and only if you want them.