My company is considering migrating from our aging on-premise Exchange server to Exchange online via Microsoft's O365 offering. One of the issues that our consultant has described to us is that when we migrate there isn't a good way to sync passwords with our on-premise active directory server. Essentially, he said there is a way to sync the two, but if the internet connection or domain controller on premise go down, it will kill our email service (which removes one of the biggest benefits of moving to the cloud). Is this the case? Is there a way to sync passwords, without having email dependent completely on the on-premise setup?
I find it difficult to believe large companies would put up with this. I'm hoping my question makes sense and that there's a good way to do this! Thank you for your help!