we would like to apologize to our users who have enabled "watching notifications" — as a result of an inconsistency in our code our servers started processing malformed activities and sending emails to unrelated users.
Some of our users might have received a few copies of a similar message.
This week we are improving many aspects of sending emails as I have blogged earlier this week, and this uncontrolled mailing came as a side effect.
We are sorry again for polluting your mailboxes. We should continue sending regular notification emails within minutes.
UPDATE: It looks like only a small fraction of users has been affected, these with low user ids.