Outlook problems when adding an external ICS file in hybrid. Kills syncing, Invite disappears

Question

We are a Hybrid organization, Microsoft 2016 exchange servers Cu23, Office365, Proofpoint, Digital Guardian and users are on 64 bit office versions.

Exec admin has permissions from the exec as a delegate. We've also given her Editor permissions w/Delegate - can view private items.

 

Both the exec and the executive admin have shared calendar improvements turned off.

 

 

Run down:

An executive admin receives flight/travel itineraries from AMEX. They come in as an email with an ICS calendar file. The exec admins takes the ICS file and drops it onto the calendar. As soon as she drops the calendar entry outlook breaks.

 

When shared calendar improvements are the break looks like this - User can't sync meetings anymore to OWA. She can add a calendar entry manually on the desktop and it will never sync to OWA. When she creates it in OWA it syncs to desktop. - Another time It actually broke owa when she tried to add a manual entry and it would throw an error. Then after 5 minutes she would receive "You don't have permissions in the desktop version." User then can't add anything to the calendar.

 

When shared calendar improvements are off the break looks like this - User drags and drops the ICS file - It sometimes will stick in the calendar but eventually disappears and won't sync to owa. Sometimes she drags it and it never appears on the calendar. She can still add items to the calendar and it will sync back and fourth between owa and desktop. When she tries to drag and drop the ICS file (Cannot copy the items, You don't have the appropriate permissions to perform this operation)

 

 

 

The fix - I have to completely blow out the outlook, remove the permissions in PowerShell and re-add them. Then rebuild the profile. Sometimes the rebuild doesn't work and we have to remove the calendar, remove the permissions then rebuild it, re-add permissions....

 

 

Fiddler- In fiddler when this happens we can see a 401 unauthorized error....

Proofpoint email security - Email comes in fine, no problems

Digital guardian - Disabled for the user, we've noticed DG kills outlook - Had more issues we worked through and once the user was in the bypass group, there was a lot less issues.

 

Answer 1

Hi @White rabbit admin ,

We are a Hybrid organization, Microsoft 2016 exchange servers Cu23, Office365, Proofpoint, Digital Guardian and users are on 64 bit office versions.

Are both the exec and the executive admin's mailboxes located in Exchange Online?
What's the build number of the Outlook client they are using? You can view the version information via File > Office Account > About Outlook.

Besides, below are some steps you can try and see if there would be any improvement:

1. Instead of dragging and dropping the .ics file, download it and then follow the steps mentioned in this link to import it to Calendar.
2. Turn off Cached Exchange mode and see how it goes.

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