I would like to use multiple mail accounts in the online version of Office 365 (Mail section of login.microsoftonline.com). At the moment, I can just log in with one account. If I want to check the mail belonging to an other account, I have to log off and log in with the other account. It is not possible to open two different accounts: when you open login.microsoftonline.com in a second tab, it automatically logs in to the account that was already open in a first tab. Are there any alternatives to circumvent this situation (online)?