Throttle failure emails, or provide a way for hosts to temporarily pause them.

[getsource]

At the moment, when a tests start to fail, a host will receive an email to let them know this is the case.

The trouble is that this can result in an email sent with every WordPress commit when a host is already aware that there is a failure.

Currently, the only way to pause this is for a host to stop reporting until something is fixed. This is problematic because it'd be great for there to be .org visibility into failing tests, to find out when a change in trunk/master affects hosts.

A couple ideas:

• Throttle emails to once per day, or couple of days, rather that every commit
• Provide a way to acknowledge that a host knows there is a failure in some way, and pause the emails temporarily
• Something else entirely?