All of those 400k people were notified because the author tagged a group containing 400k people. For every comment, 400k emails went out. I never commented, bu

All of those 400k people were notified because the author tagged a group containing 400k people. For every comment, 400k emails went out. I never commented, but I received an email for every comment in that issue. The email queue was so backed up that I was receiving emails for quite some time after the issue was closed.