An easier way to import lots of email
One of the main challenges in moving from an on-premise Exchange installation to the Microsoft hosted Office 365 service is data migration. The slowest method to import data from existing Exchange mailboxes to Office 365 is to use Outlook to upload the data directly to Office 365.
Microsoft caps the import speed at roughly 500 MB an hour per mailbox from each instance of Outlook which can easily cause problems due to time and logistical constraints – even over a long weekend. It is more efficient to use their new PST Import Tool which involves uploading all the data to a temporary Azure location and then starting a mass import. The procedure for bulk Office 365 imports is described in this article.