We don’t send an alert for that specifically. The alerts we do send can be found on the Wordfence Dashboard > General Options section where it says “Email Alert Preferences”.
Just a FYI, throttling is generally a better option than blocking because any good search engine understands what happened if it is mistakenly blocked and your site isn’t penalized because of it. Make sure and set your Rate Limiting Rules realistically and set the value for how long an IP is blocked to 30 minutes or so.
I generally set my Rate Limiting Rules to these values to start with:
If anyone’s requests exceed 240 per minute
If a crawler’s page views exceed 120 per minute
If a crawler’s pages not found (404s) exceed 60 per minute
If a human’s page views exceed 120 per minute
If a human’s pages not found (404s) exceed 60 per minute
How long is an IP address blocked when it breaks a rule 30 minutes
Remember there is no hard and fast, one size fits all set of rules for every site. These are just a good place to start. During an attack you may want to make those rules stricter. If you see visitors, like search engine crawlers getting blocked too often, you might want to loosen them up a little.
I hope this helps.
Tim