This user's on-premises mailbox hasn't been migrated to Exchange Online

Question

This user's on-premises mailbox hasn't been migrated to Exchange Online. The Exchange Online mailbox will be available after migration is completed.

How do I get the mailbox provisioned without setting up a hybrid environment?

Answer 1

Use the Synchronization Rules Editor to set the msExchMailboxGUID attribute to NULL in the cloud, while leaving it the same on premise.

https://support.rhipe.com/portal/en/kb/articles/how-can-i-set-msexchmailboxguid-attribute-to-null-1-10-2019#Answer