Office365 FAQs - Will there be any downtime for users during O365 transition?


All applications will remain available to the user throughout the migration, however some of your data may be unavailable for a short time as we move it to the cloud. Example: the .pst files in your “My Documents” folder will be ingested into your O365 mailbox; because these files represent a large amount of data that exists on geographically dispersed servers, migrating them will be time intensive and will require a combination of some service degradation or down-time.