Slow Office365 Tenant to Tenant migration.
I want to migrate slowly from O365 Tenant A (Exchange Online) to a separate O365 Tenant B (Exchange Online).
Users at the original tenant use the DNS domain firsttenant.com, users at the the second tenant use the DNS domain secondtenant.com.
Some challenges are:
- I migrate and cutover User1 to Tenant B. Now he is using the domain secondtenant.com. How the users not migrated will send emails to User1? One idea that I have is to setup the targetaddress field of that mailbox, so it will forward the emails for that account. And in this way the non-migrated users will be able to send emails seamless to the migrated users.
- Now User1 needs to send emails to Non-Migrated users... What would be the idea here? I Can create a temporal contact on Forest B for all the accounts (and delete them gradually when these mailboxes are migrated). Another option in my mind could be to always send emails to the addresses ending with firsttenant.com until the migration is completed. But is anyone of these ideas going to break the autocomplete/cached names in Outlook?.
Any others alternative for this?