I know the subject is quite confusing, but this is exactly I was told to find out. In Active Directory, I can add several email addresses under the same domain in my account, such as me@mycompany.com, info@mycompany.com or question@mycompany.com, but how can I share the mails from one of the address I created with my boss? What I meant was when some people send an email to question@mycompany.com, we want both of us to receive this email. At first, I thought I just need to add this address to both of our account, but apparently this is not going to work. It gave me an error message " This email address is already exist in this organization" when I tried to add question@mycompany.com to his account. Any help will be appriciate.

Create a mail enabled universal distribution group and then add your account and your boss's account as members of that distribution group. The SMTP address of the distribution group should be question@mycompany.com