On prem to Azure Ad sync ----ok
AD Users already sync to Azure AD---ok
Planning not to use hybrid exchange because of future email attributes control difficulty.
I found that the cutover mailbox migration grey out, I can't use cutover migrate. After I turn off Azure Dirsync, the cutover migration is available now from class Exchange Admin Center and I successfully created mailbox migration batch.
Currently, the Public DNS is still pointing to the on prem exchange 2016 Server.
I am in the step of evaluating the Exchange online.
After I cutover migrate all mailboxes to exchange online (before I change the DNS MX and A records "Autodiscover") >>> Is my on prem exchange 2016 Server are still available to users????