For accounts that have CRM Integration enabled, the CRM Username is used to identify the appropriate sender of an email when CRM Owner is selected in the From section of the Email Action.
The entry for the CRM Username should match the EXACT Username used to log in to the selected user's CRM account. If the Username entered in DemandCenter does not exactly match the actual CRM Username, the two applications will not sync correctly. A given CRM Username may not be assigned to more than one DemandCenter User per account.
To adjust the CRM Username, go to Settings > User Management. Next, double-click on a user. Then, provide the CRM Username next to the CRM Username field.