Is this expected?
In Office365 I have two domains, mydomain1.com and mydomain2.com. At present mydomain1.com isn't really doing anything, just sitting there, however mydomain2.com is the one that I have federated and the one that I am playing with. mydomain1.com however is in use elsewhere, it's our onsite Exchange server and is working happily. When I try to email firstname.lastname@example.org from email@example.com however (remember this is the one I am using in O365 for email) it's just bouncing back.
Is this because Office365 sees mydomain1.com as being 'local' to it even though its role isn't set as email, and because any email addresses don't exist for this domain in Office365, it's throwing a wobbly?
Hopefully this makes sense. :-S