Disable Outlook Mentions Company Wide

[GianniAzure]

Hi Everyone,

We have a customer who wishes to disable @ mentions in Outlook. They share very confidential information so do not want to risk this information being sent to the wrong person.

In respect to this, we have a deployed a policy that applies the reg key 'ShowAutoSug' with a value of 0 and that works well.

However, I am looking for a way to disable @mentions company wide.

I of course know the setting individually within the Outlook client but cannot see any ADMX entry or Registry DWord I can use to disable this en-masse.

I speculated this was maybe a 365 tenant change instead but cannot see anything confirming that either.

Any guidance would be much appreciated.

For clarity, attached is a screenshot of the Outlook setting I am trying to deploy company wide (either through GPO/Registry)

[#2]

@GianniAzure 

How about considering force configuration in Outlook?

Open Outlook > File > Options > Mail > Send Messages > Uncheck “Suggest names to mention..”

[#3]

Please could you expand on that?
That is the setting I want to enforce, how would I force that configuration to all users/devices?