Hello Jason
As far as of now, it appears as if I am the only one still left with those issues. If this is due to that the user previously spoken of has deactivated his/her parallell account or because of some other reason I cannot tell.
As of now though, there is for sure a problem with my account, where I receive doubles, triples and sometimes up to 16 copies of the same email.
What are the best practices for solving this kind of coexistence problems of parallell Microsoft accounts, since there is an active subscription tied to the other account than the one being sign-on credentials for my Office365?