Google has rolled out a new update to its Google Apps Accounts which now allows you to now login with up to 10 multiple accounts. Allowing you to access your Google Calendar and Gmail alterative accounts at the same time.
Previously the limited on multiple accounts was set to three but unfortunately the new update does still restrict a number of Google features to only one login. Such as AdSense, AdWords, Blogger and App Engine to name a few.
Once you hace signed in to your 10 accounts, Google automatically display an error message:
“You are already signed in to the maximum number of accounts. If you want to use another account you must sign out of all Google Accounts then sign in to the account you want.”
If you would like to enable multiple sign-ins you need to enable the feature within your Google accounts settings. More information is available from the Google support blog.
Source : Google Operating System