Once I downloaded Windows 10 my Outlook email does not function properly. Also, my iCloud address book was removed although I cannot find where it went. It contained distribution lists for a non-profit organization I belong to. When I send an email I never know if it actually sent. My sent box comes up empty and the messages I sent remain in the Outbox although they actually did go to the recipient. It sounds crazy but the revolving circle keeps going on the outbox and it takes forever to see what is still in there.