Microsoft has confirmed hackers had full access to selected Outlook email accounts between 1 January and 28 March , according to a follow - up statement that contradicted a previous notification . In response to the breach, Microsoft is warning affected people to watch out for phishing emails, and recommends that people change their password. It came after Motherboard 's discovery that hackers could read email content , but Microsoft said that was possible only for about 10 % of affected Outlook accounts . The breach occurred after the theft of login credentials from a member of Microsoft 's customer support team . The firm said the stolen access has now been restored .
Microsoft has confirmed hackers had full access to selected Outlook email accounts between 1 January and 28 March , according to a follow - up statement that contradicted a previous notification . It came after Motherboard 's discovery that hackers could read email content , but Microsoft said that was possible only for about 10 % of affected Outlook accounts . The breach occurred after the theft of login credentials from a member of Microsoft 's customer support team . The firm said the stolen access has now been restored .