I'm in the final phase of planning our Exchange 2013 to Exchange online Hybrid deployment.
We require that all primary smtp mail routes through our email gateway service (Mimecast) for compliance purposes.
What I would like to understand is when enabling this option using the HCW , will it also apply to our non primary SMTP domain mailbox users like our @***.onmicrosoft.com domains ?
In the HCW you have to select the domain(s) that you are using for hybrid. Those domains are then used in the connectors that are created.
If you do not specify the domain, it will not be included on the connectors, and thus will not be impacted by the mail routing changes.
The same is true for any connector that is going to be pointed to mimecast, you have to specify what domains it applies too. In normal configurations the .onmicrosoft.com would not be included.
Thanks Adam , that's a clear answer. Appreciate it.