Remove/disable S/MIME from O365 environment

Question

Hi There,
I was wondering if there is a way to remove or disable S/MIME from O365 environment as we have moved onto OME/Sensitivity Tags.

Answer 1

I would do the reverse of :
https://learn.microsoft.com/en-us/exchange/security-and-compliance/smime-exo/configure-smime-exo

If you set the requirements to $false:
https://learn.microsoft.com/en-us/powershell/module/exchange/set-smimeconfig?view=exchange-ps

See what is set:
Get-SmimeConfig

it should disable the clients using it

Also disable client usage if necessary here:

https://learn.microsoft.com/en-us/exchange/security-and-compliance/smime-exo/configure-smime-exo#step-5-configure-email-clients-to-use-smime

Answer 2

Hi @Ajaz Khan

Agree with the suggestions above from Andy, and one of the steps introduces is publishing user’s certificate to the Exchange Online GAL (Global Address List) using Outlook.
If not published, users will not be able to exchange S/MIME encrypted messages. This can be considered as a method as well.

How to Configure S/MIME in Office 365

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