Hi Bourne,
Yes all domains has been added and verified in office 365, our scenario was as follows:
we were having exchange 2010 as a hybrid deployment with office 365 and after some time once we have moved all users to office 365 we have uninstalled our exchange 2010 from our on premises, how ever there is still one exchange 2010 in our on premises which as acting as smtp relay for line of business applications to be send email to office 365, and we do not have any users mailboxes in our exchange 2010.
Thanks
