In this post I want to talk about Exchange Online and OWA redirection for user who have a mailbox still on premise.
When you set up your hybrid environemt the wizard will automatically set your on premise TargetOwaURL to https://outlook.com/owa/domainname. You can see this by doing a get-organizationrelationship | FL in the shell.
This is the link that a user who has been moved from on premise Exchange into Exchange Online sees when they try to access their mailbox through the on premise OWA url.
This may not be set by default in your tenant. If you do a
get-organizationrelationship | FL
in Exchange Online you may see a blank value. This is where you can add your onprem OWA url if you see fit so users who are onprem and try to access the cloud OWA will be redirected.
There is a catch though. If the on prem user IS NOT licensed for exchange online in the cloud then this redirect URL will not show up, they will only receive the " :-( Something Went Wrong" screen. See below for examples.
So even if you have a few fully onprem users and wish to use this feature you are still going to have to pay the piper for a license.