How to use S/MIME certificate in Outlook on the web and desktop client

Copper Contributor

Hi there,

 

I want to store a s/mime email certificate for a user centrally in exchange online so that it is automatically pulled when I want to use outlook on the web, mobile or desktop. Is this possible at all and if so, where and how do I have to set it up?

 

I have not found anything in my search so far, I only found this link, but it talks about a local AD, which I do not have.

 

Any ideas?

4 Replies

Hi @MarcelThieme,

If you are using Exchange Online without an on-premises Active Directory (AD), you can still configure and use S/MIME email certificates for users. Here are the short steps:

  1. Access the Exchange admin center (EAC):

    • Go to the Microsoft 365 admin center (admin.microsoft.com).
    • Select "Exchange" from the admin centers menu.

  2. Configure S/MIME settings:

    • In the EAC, go to "Mail flow" > "Message encryption" > "S/MIME."
    • Enable S/MIME by checking the "Enable S/MIME signing and encryption" box.
    • Choose the desired options for signing and encryption.
    • Save your settings.

  3. Upload the user's S/MIME certificate:

    • In the EAC, navigate to "Recipients" > "Mailboxes."
    • Select the user mailbox for which you want to upload the S/MIME certificate.
    • Click on "More options" (•••) in the mailbox details pane and choose "Manage S/MIME settings."
    • Use the "Import certificate" button to browse and locate the user's S/MIME certificate file.
    • If needed, enter the certificate password and click "OK" to upload the certificate.

Once the S/MIME certificate is uploaded, you should be able to use it with Outlook on the web, mobile, and desktop clients.

Please click Mark as Best Response & Like if my post helped you to solve your issue.
This will help others to find the correct solution easily. It also closes the item.


If the post was useful in other ways, please consider giving it Like.


Kindest regards,


Leon Pavesic

Hi Leon,

thanks for your help. I'll test it soon and give you response and mark it as best response and like :-).

Best regards

Marcel
Those options don't seem to exist anymore... any update?
I found that under Mail flow, the "Message encryption" and "S/MIME" options no longer exist. I cannot find MIME anywhere in the control interface.

Any suggestions are welcome.