We currently have a hybrid on-prem/Office 365 environment.
Our Exchange is on-prem. Users are synced to an Office 365 tenant using Azure AD Connect so they can use Teams/Sharepoint etc.
We want to migrate to the cloud and remove the on-prem exchange.
For legal reasons, however, we have to move everything to a different Office 365 tenant.
What would be the best way to do this? Migrate everything to the cloud first, and then migrate to the new tenant, or migrate to the new tenant directly?
From what I've read it's not possible for an e-mail address to exist in two tenants, so we can't just set AD Connect to the new tenant without first removing it from the old tenant, right?
Instinctively I would set up users and accounts first in the new tenant first before migrating mailboxes and switching over domains and MX records, but I don't think that's possible.