Setting threshold for Mail Queue Size Exceeded doesn't "stick"

I’ve had two individual email accounts get compromised in the last 2-4 weeks and want to be able to catch this sooner, rather than later. One day it would be nice to have some autoblocking of IPs if a threshold of emails per minute is reached, but in the meantime I just need to know about it sooner.

I set it to a low 50 emails in queue, but after saving it returns to the main alert screen. When I got back in to that alert configuration it’s back at 1000.

Ok, I just set it to 5000 and saved. Then tried 500, it worked, then tried 100, it worked, then tried 50 again… and now it’s working.

Not sure what happen, but it seems to be set now.