so I've searched forever for a solution for this problem.
Our customer is using mailboxes in Exchange Online with Outlook 2016 on a Server2016 Remote Desktop Session Host Farm.
User profiles are located in User Profile Disks. Indexing is activated. Cache is - for some users - activated.
The performance is not good and Outlook keeps "not responding" occasional on simple tasks like sending an email with a small attachment (<1mb).
What is best practice for this setup? There are different opinions on this.
Some say, indexing is not supported for cached mode on roaming RDSH users. But without indexing the performance is unbearable.
Others say, Outlook is not recommended on RDSH and instead OWA should be used, which is no option whatsoever.