How do I enable and use S/MIME for Outlook (web)? What are the prerequisites for doing so?

Question

I'm using Microsoft 365 Business Premium with no on-premise AD - does this support S/MIME, and if so, how does one enable it for use within Oulook web? I have no problems obtaining the certificates - and S/MIME worked well with Google Workspace - but the myraid of documentation for Microsoft 365 is both confusing and annoying.

Many thanks,

Martyn

Answer 1

With all due respect, Microsoft, this isn't acceptable on a business product. There are enough Mac users using Office 365 to warrant implementing S/MIME in Outlook on the web. It's not good enough to say 'Macs aren't supported' when we're talking about a huge user base and an important security/privacy feature like S/MIME certificate. This is especially the case given that it's possible to use them in most of the different email apps available on a Mac, including Outlook for IOS. I also use Zoho workplace and S/Mime are simply uploaded in two seconds. After that, the certificates are available and automatically used when sending email on then web or through their client software. It take 30 seconds to set up, unlike the incredibly complicated and convoluted way that MS requires.

At the very least, would you please let customers know whether S/MIME support for Macs in the web app is in your near-future roadmap. This will allow users like myself to plan and make alternative choices for our businesses.

Answer 2

Why isn't Microsoft supporting S/MIME on Mac? The whole world uses Outlook now and a large portion of that customer base uses Mac. Can you please enable S/MIME for Mac?

Answer 3

Hi Movielad76,

Good day.

Thank you for posting to the Microsoft Community. We are glad to assist.

S/MIME (Secure/Multipurpose Internet Mail Extensions) is a powerful way to enhance email security by digitally encrypting messages and ensuring their integrity. Let’s walk through the steps to enable and use S/MIME in Outlook on the web:

Prerequisites:

• Windows desktop device: Outlook on the web requires a Windows desktop device to support S/MIME. Unfortunately, S/MIME isn’t available in Outlook on the web for Mac, iOS, Android, or other non-Windows devices.
• Certificate: Obtain a certificate (sometimes referred to as a key or digital ID) from your IT administrator or helpdesk. Your certificate might be stored on a smart card or as a file on your computer.

Install the S/MIME Control:

• Open Outlook on the web.
• Go to Settings (gear icon) > Mail > S/MIME.
• Look for the message: “To use S/MIME, you need to install the S/MIME control. To install it, click here.”
• Click on “Click here” to install the control.
• If you receive an encrypted message before installing the S/MIME control, you’ll be prompted to install it when you open the message.

Additional Notes:

• Chrome Compatibility: To use S/MIME on Chrome, your computer must be joined to a Microsoft Active Directory domain and have a Chrome policy to include the S/MIME extension. Check with your IT administrator to confirm this.
• Internet Explorer, Edge, and Chrome: Depending on your browser, you might see prompts to allow the domain to use S/MIME. Follow the prompts to trust the domain and enable S/MIME.

Please checkEncrypt messages by using S/MIME in Outlook on the web

Remember that S/MIME adds an extra layer of security to your email communication, ensuring that only authorized recipients can read your encrypted messages and verifying the authenticity of your emails through digital signatures.

I hope this helps let me know if this is contrary to what you need, I would still be helpful to answer more of your questions .

Best Regards

Community Moderator

Answer 4

Except there is no option Settings-Mail-S/MIME. Because I dont have a sub or what??

![](https://learn-attachment.microsoft.com/api/attachments/8baca6e5-2337-4764-9658-829544d04352?platform=QnA

Answer 5

Darn. I'd have thought that because of open nature of the web, Microsoft wouldn't be that awful and limit it to their own platform whereas Google handles it with ease. Looks like I'm going to have to fork out for a Windows machine. *Makes sad Tim Cook noises*

Thanks for your help, nonetheless - it's something that I can use when I next go on a Windows machine.