My solution was just stop using Outlook as main mail. They have a problem of bots being able to create accounts so they can spam yours and because are from outlook they are not stopped by any (if even exists) anti-spam filter. On other services you have to verify your account by mobile or something so bots cannot do this so easily.
I even removed outlook mail from being synced on my devices. Bye bye outlook mail while this is not solved.
And if I had to hire some service for professional use, of course it would not be this one, given my experience as user, cannot risk to get this in my professional mail.
So, they have to solve both the automated creation of random accounts so easily and adding some effective anti-spam filter, i.e. sending to a spam folder messages from recently created accounts not in your contacts.