Someone is sending mails with watch only address in attachments. I am not sure about the email content but one of my client lost 0.5 BTC due to mistake.
He have downloaded attachment file some time ago and completely forgot about that, today when blockchain.info was down he downloaded electrum and thought to import keys, by mistake he imported "hackers" wallet. He didn't knew about "watch only address" feature and ignored it.
He bought bitcoins from me and I sent him funds on this address 1MLk8Hc8tJMaEih7T5jQ3H2jNy1w1mjdKy, few minutes later payment was forwarded to 15BHe7Lbi9BfjY2qvkC6DBSWXMowXiGBZh automatically after it reached 1 confirmation.
Not sure how but he have stolen many bitcoins from users.
http://blockr.io/address/info/15BHe7Lbi9BfjY2qvkC6DBSWXMowXiGBZh Balance
69.49450923 BTC
Total received
137.43115554 BTC
I will update this thread soon with email content and more details.
Just wanted to warn everyone that do not download anything from random mails.