Windows Mail client users who tried to add a new iCloud account recently couldn’t complete the action due to error code 0x800706be or infinite loading times.
Workaround: Add iCloud account in People app, it adds successfully and you can then add iCloud account anywhere, when you go back to Calendar app the account is there.
Reference: Microsoft Answers Forum: Windows Mail client either spits out error “0x800706be” or loads forever when trying to add a new account.
