We’ve had a few instances where a user could not receive mail into their Exchange Online mailbox. Upon investigation we noted the onmicrosoft.com address is the primary SMTP address for the user and that the remote mailbox object is not available in Exchange on premises. To resolve this do the following: Open Active Directory Users and Computers (dsa,msc from start -> run) Click on View -> Advanced Features Do a search for the user who has the issue as per above Right click on the user and choose properties Click on Object and make a note of the path Close the search you made. Now navigate in Active Directory Users…