Open Mail, then on the Mail menu, click Add Account...
Select Exchange and click Continue.
Type your Name, Email Address (i.e. YourEIDfirstname.lastname@example.org) and Password. Click Continue.
Apple Mail will try to access O365 server by your account. If the information provided is correct, this account will be set up successfully. Click Continue.
When Account Settings appears, type YourEIDemail@example.com (e.g. firstname.lastname@example.org)
to the text box User Name (it is @ad.cityu.edu.hk instead of @my.cityu.edu.hk). Type
outlook.office365.com to the text box Server Address. Click Continue.
If the information provided is correct, this account will be set up successfully. Click Continue..
Select the apps to use with this account. Click Done. Now you can send and receive emails by Apple Mail.