Did you ever need to find in your Office 365 tenant : what objects are using a specific email address or UserPrincipalName ? what objects are preventing an AD account syncing ? where are them located in your tenant : in Users, in Contacts or in Deleted users ?
Check if an email address or a UserPrincipalName is already used by another account in your Office 365 tenant
Jean-Marie AGBO
agbo.blog 