Set global ratelimit & Delayed in incoming emails

Johnd

1) How do I set global rate limits for all domains?
2) For a specific domain, the incoming emails have a long delay, how to check what is the reason?
- Domain 1: no problem
- Domain 2: too much delay for incoming emails

Thanks

Johnd

I managed to find x the delay,
1) How do i set global rate limit for 50,000 each domain?
2) Is it possible to get the total of outgoing emails for a domain?