Microsoft on Thursday introduces a hacking alert system to its Windows Live Hotmail email service alongside banning common passwords. \"When someone\'s account gets hijacked, their friends often find out before they do, because the hijacker uses their account to send spam or phishing email to all their contacts,\" said Microsoft in a blog post. The new security feature adds a \"My friend\'s been hacked!\" option in the \"mark as\" menu in Hotmail and also enables users to report hacked accounts via the junk mail filing screen. Then an alert will be sent to Microsoft, which will \"make sure the account can no longer be used by spammers and activates an account recovery process to allow the owner to take back control the accounts.\" Users can report any email account as compromised and Hotmail will provide the information to other email providers like Yahoo! and Gmail, said the blog. Meanwhile, Microsoft said Hotmail will roll out a feature to prevent users from choosing commonly used and weak passwords, such as \"123456,\" \"ilovecats\" and \"gogiants.\" Users who currently use a weak password will be asked to change to a stronger one in the future. Hotmail, first launched in July 1996, is one of the first free email providers, and was acquired by Microsoft in 1997 for an estimated 400 million U.S. dollars. According to statistics released by comScore last August, Hotmail was then the world\'s largest web-based email service with around 364 million users, followed by Yahoo! Mail (280 million) and Gmail (191 million).