I have a client who connects via RDS to a handful of virtualized session host servers we host in our datacenter.

These session host servers have Office 2016 installed and Outlook is configured for each user to connect to the users Exchange 365 mailbox.

The users are experiencing poor performance in outlook which boils down to these three things:

  • Outlook not responding, 'whiting out' and/or crashing when sending mail.
  • Outlook not responding, 'whiting out' and/or crashing when navigating through folders and reading items.
  • Regular warnings that 'Outlook is trying to retrieve data from the server'

The session host servers have an abundance of RAM and CPU allocated and are nowhere near capacity, so I can comfortably rule that out.

We've got some users using OWA at the moment to see if that is more stable and we've got our 365 provider looking into it on Microsoft's behalf, but I'm wondering if this is something that other people have experienced in this kind of environment or even at all when using Outlook 2016 and Exchange 365.

The issue has been ongoing for some time and It seems to be affecting all users. My client has already asked about the possibility of moving back to a hosted exchange solution, which I wish to try and avoid, so any help is greatly appreciated.

  • Hi, You need more information. Please run a processmonitor and watch what cause the lag please – yagmoth555 Sep 17 '18 at 13:09
  • Is Outlook configured in cached mode? If not, that's likely the cause of your performance problem. – joeqwerty Sep 17 '18 at 14:53

I would look at FSLogix - which helps you run your VDI setup more like traditional desktops (with Outlook in cached mode) when it comes to Office Pro Plus. We recommend it now with all Citrix deployments, but it works with RDS as well.

Make sure your clients are updated. Check the known issues, and release notes to be sure you are not fighting a known issue. Out of date clients can cause you headaches with all sorts of issues when it comes to Pro Plus clients.

Try checking autodiscover. Run the autdodiscover checks from a user session and be sure you don't have any issues there. If all mailboxes are hosted in Office 365 be sure your DNS points directly to Office 365 and the Active Directory SCP are null, or also point to Office 365. When all mailboxes are migrated you don't need the re-direct functionality from the Hybrid Exchange server (which most orgs will have with directory synchronization). I usually see this issue occur with new connections, but sometimes it will surface in the normal day to day Outlook usage, causing delays.

Depending on where you are it could just be latency issue. Exchange Online is now much farther away then their servers were. This is where cached mode in Outlook really helps. If your servers are in one location and backhauling your traffic to another site, it could be adding to your troubles. Microsoft has peering points all over the world to help with latency, but when you backhaul traffic to another location and out you are not hitting the closest peering point and you're adding latency into the connection. If something like this in place - try to split out that Office 365 connection to a local internet point and see if that helps.

Consider deploying an Office Telemetry Server. Just to monitor the RDS deployment, a small server with SQL Express is probably more than enough, but it will also help tell you if add-ins or plug-ins are causing you issues.

And you can enable Outlook verbose logging as well. If you want to go this route, I would open a support ticket first, Microsoft will take the log output and analyze it for you and let you know what if anything they find.

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