This error occurs because Outlook downloads all the messages with attachments when you connect an IMAP email account with it. Though it is not for every email account, the error notification says 11 of 14 tasks have been completed successfully with reported error 0x800CCC0E. Many users often receive an error “Outlook cannot synchronize subscribed folders” when connecting IMAP emails with Outlook. But, having many folders and messages with attachments often makes Outlook slow, especially when you configure many IMAP accounts with Outlook. Users can easily configure other email accounts like IMAP, POP, Office 365, or Exchange with MS Outlook and access all their emails/messages in one place. This gives that external user access to other content in the parent site we want to restrict, so this is not an option.MS Outlook is a widely used email application, and there is a reason for that. The only thing that seems to fix the issue is to add the external user to the calendar's parent site as part of the members group. I've tried the conventional wisdom of deleting the calendar from Outlook and adding again, but always get the same result. 'Task SharePoint reported error (0x80070005): You do not have permission to view theis SharePoint List. The calendar is added to Outlook, but any attempts to sync results in an error message: They are able to browse the calendar via Internet Explorer, but if they click the Connect to Outlook button in SharePoint, Outlook prompts for a username/password that can never authenticate. I've broken inheritance on this calendar and granted Read permissions on the calendar to these non site members. I have a SharePoint 2013 calendar that needs unique permissions on it, allowing people who have NOT been granted access to the parent site access to this calendar.

Outlook 2016 sync issues 0x80004005