From the documentation of the Exchange client app store module:
Impersonating another user means you connect to their mailbox using your own login information. If you want to impersonate another user, you will have to select the Use impersonation option as well as enter the mailbox name of the user you want to impersonate. You will need to have impersonation rights for that user. Consult your Exchange administrator on how to set this up.
This is mostly a 'how to I manage an Exchange server' question and not so much a Mendix question. I don't quite remember how to set up those rights but there should be information on this on the internet. But yes, it is possible.