Outlook 365 App has items in the outbox and does not send them

Outlook 365 App has items in the outbox and does not send them. Updates from the exchange server are slow and sluggish. Solutions: Disable IPV6 in your network adapter. Other Procedures are to repair the ost file, or to rename and reload the ost file. Be also carefull with online backup programs so that they do not touch/backup your ost file.