ErrorNonPrimarySMTPAddress - how to fix?

Description of the error code "ErrorNonPrimarySMTPAddress"

Domain: Exchange 

Code: ErrorNonPrimarySMTPAddress

Type: Configuration error (You are often able to resolve this type of error.)

Description: The calendar's email address used to integrate the calendar with AskCody must be the calendar's primary SMTP address. 

Possible solution: Please enter the correctly formatted SMTP address for the calendar. Ensure that the address is written as an email address, for example,