You may have a custom application whose purpose is to pull information from Microsoft Exchange Server. This includes information such as Out of Office and Free/Busy data. However, the custom application cannot perform functions of this kind.
|Impersonation Rights for Exchange Web Service Applications||E2010-MSO Self Service - EWS Application Impersonation||SG members (Service Accounts) will be granted impersonation rights to all mailboxes in the Exchange organization for use with Exchange Web Service applications.|
If this role group was not provisioned for you, you have to file a new Change Request to have the role group provisioned.
This is how the role group will look on the Microsoft provisioning side:
get-rolegroup "XF-CUS-EWS App Imp" | fl name,*linked*
Name: XF-CUS-EWS App Imp
LinkedGroup: DOMAIN\E2010-MSO Self Service - EWS Application Impersonation