The procedure of Set up Office 365 Mailbox on Android based phone my be slightly different based on Android device you are using but the concept will be the same. Please make sure your previous mailbox is removed from your Android device before adding new account.
1. On your mobile device, go to the Google Play Store and install the Microsoft Outlook app.
2. Open the app after it is installed.
3. Choose Add Account and type your mailbox address firstname.lastname@example.org
4. Choose Continue and enter your Password.
1. On your Android device Tap SETTINGS.
2. Tap ACCOUNTS or Accounts and backup
3. Tap ADD ACCOUNT or Manage Accounts
4. Tap Add Account
5. Tap Microsoft Exchange ActiveSync
6. Enter your Email Address and Password and Tap next
Gmail supports Microsoft® Office 365 and Exchange ActiveSync accounts, and comes pre-installed on all Android devices. To add your Microsoft® Office 365 account to Gmail:
After you add your account to Gmail, you may be prompted to set up a password via the Mobile device mailbox policies if your IT admin requires it.
If your organization uses a different email client, consult your email client’s documentation to determine whether it supports Microsoft® Office 365 and Exchange ActiveSync accounts and to learn how to set up your account.