I asked the last question in thread: http://community.spiceworks.com/topic/394665-office-365-retention?page=1#entry-4003375
Realizing after Julia from SP mentioned it, its an old thread. - Thanks Julia!
So, i've changed the retention policy in the EAC in O365, but cannot see it shine through onto Outlook on the users calendars.
Any idea how long it might take?