Once an Active Directory class object or attribute has been created, it is impossible to delete it. In simple words, as a developer, you are bound to change your code, because neither registry changes can be made nor group policy can be modified.Trying to install CU 19, and getting The operation couldn't be performed because object 'XXX\OWA (Exchange Back End)' couldn't be found on 'YYY.The action ‘Set-Mailbox’,EmailAddresses’, can’t be performed on the object ‘Steve Test4’ because the object is being synchronized from your on-premises organization. The operation couldn t be performed because object office 365 EURPR03A001.
