Outlook 2016 connects to Office 365 before cutover of Office 365 migration

A feature in Outlook 2016 will make sure that Outlook connects to Office 365 if the e-mail address and mailbox exists in Exchange Online. This can cause issues during an Office 365 migration when you still are using your current on-prem mailbox while you also require a Exchange Online mailbox in order to copy the mailbox data to Office 365. This can be fixed by adding/altering a registry value.

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