They should be able to explain why so many people received the email though. Was there a fault in the notification system or not? Are they going to send messages to the individuals which received the notification in error?

I get that direct evidence of a leak is difficult. However, a sudden surge of master passwords being known by third parties in uncorrelated accounts is a very good evidence that something happened. If that's not what happened, then what happened exactly? Was it really a bug in the notification system? Do they have evidence that the password used in the blocked login attempts weren't really the actual master password?

There is a lot of things they can do to show they are on top of things.

I did not miss that. But it's harder for me to read that as a technical statement and not more PR after the rest of the PR.

I also agree with you about the 100% confidence about not being compromised. Perhaps my previous statement was too black/white. I don't want PR or placating statements, I want a transparent status report without weasel words and which exhaustively covered the different cases (e.g. SOME of the messages were sent in error. what about the rest? Are the rest routine compromises that happen normally? Or was there a spike in compromised accounts?)