Can I implement this myself with a plugin?
Or is there a way to disable builds on test failure until explictly re-enabled

Currently "build failed / build failing" notifications took into account how previous build failed. If failure is the same or similar then notification will not be sent. Of course similar failure detection mechanism requires improvement but in general "build failed / build failing" notification should work like "first build failure after success" if build continues to fail with similar errors.

As for "first build success after failure" this event is not supported now and we could implement it.

For now it is impossible to extend number of supported notification events. However you can write you own listener (BuildServerListener) and try to deliver messages by yourself from a plugin, or you can pause build configuration from the plugin on a test failure.

Is this new behaviour with 1.2 or Agra? I have a 1.1 server which I've configured to send me mails on <All projects>, <All configurations>, - Responsibility changes, * - Build failed

With this config I receive e-mails every time my tests fail, even if there are no new failures. Should I open a bug or is this behaviour fixed in 1.2 or Agra?

Looks like a bug. TC should not send emails on same failure (i.e. if same test failed with similar stacktrace or same error appeared in logs and so on). Could you please submit exceptions from a couple of builds for which you received email notification?

Created a new issue: TW-1649

First failure after success & first success after failure are now supported for all types of watches except build with my changes.

Sounds good, but why not for "builds with my changes"? Is it a technical limitation or is there something I'm missing?

We did not see any valuable use cases when it is needed for builds with my changes.
It is not clear why somebody would like to subscribe to "Notify on the first successful build after failed" for builds where he is committer. In most cases build committer either do not want to be notified about successful builds at all or wants to be notified on every successful build with his changes.

As for "Notify on the first failed build after successful" this could be useful in some cases because when a build fails TC will notify each committer of this build on any subsequent failed build. However there is "Ignore failures not caused by my changes" option. If this option is turned ON then TC analyzes how build failed and if failure is the same then previous build committers will not be notified. So it seems that this option covers more use cases. That is why we decided to disable these options for builds with my changes.

Here is our use case for the situation where "Notify on the first successful build after failed" should work also for notifications for my changes.

• Jack, Joe and Jill are developers. All of them have chosen: "Notify about failed builds with my changes"
  
• Build 5 contains changes by Joe and Jill
  
• Build 5 fails. Joe and Jill will receive an email about the failed build. Jack will not.
  
• Joe notices that it is his change that broke the build. As it is a simple change, he will simply fix it without explicitly clicking "Take responsibility". (This happens pretty easily)
  
• TeamCity detects the commit and starts Build 6
  
• Build 6 is successful. But no notification is sent to anybody.

A notification about the first successful build should be sent to Joe and Jill because they received the original failure email. After that, they will only want to receive an email when a build with their changes in it fails the next time.

We considered this use case, but at the moment it requires too much effort, we decided to move it to the next release, please watch for: TW-4258.