Getting error alert when setup mailbox in CRM

Question

I am new in Microsoft Dynamic CRM and my work is to send automatic email when a new user is registered in contact in marketing list from my web site. I have successfully added person details in Marketing list from my web site. now i am trying to setup my mailbox but I got this error when i tried to setup the exchange server:

 

"The email message "Test Message" cannot be sent because the email address of the mailbox Sanjeeb Sapkota is not approved and the mailbox has been disabled. A notification about this is posted on the alerts wall for the owner of the email server profile Microsoft Exchange Online."

 

Can anybody help me for this.