Microsoft S/MIME

Microsoft S/MIME

Performs S/MIME digital signing, encryption and decryption for email messages in Outlook on the web.

What is Microsoft S/MIME?

Microsoft S/MIME is a secure email extension for the Edge browser that simplifies security. It allows users to send digitally signed, encrypted and decrypted email messages through Outlook on the web. This guarantees email authentication, integrity, and confidentiality. Enhance your email security with Microsoft S/MIME.

Stats date:
Rating: 2.20 (552)
Version: 20.20.514.1 (Last updated: 2020-05-19)
Creation date: 2020-05-19
Manifest version: 2
  • https://*/owa/*
  • nativeMessaging
  • activeTab
  • storage
Size: 56.89K
Risk impact: High risk impact
Risk likelihood: Low risk likelihood

Other platforms

Not available on Chrome
Not available on Firefox

ChromeStats Rank


Performs S/MIME digital signing, encryption and decryption for email messages in Outlook on the web.

User reviews
User reviews summary
These summaries are automatically generated weekly using AI based on recent user reviews. Edge Add-on Store does not verify user reviews, so some user reviews may be inaccurate, spammy, or outdated.
  • Works fine if the private key is imported
  • Does work in Edge when used correctly
  • Step by step instructions in the AF portal are helpful
  • Doesn't seem to work for most people
  • No further instructions after downloading
  • Doesn't work on Mac
  • Need to manually add the Outlook URL(s) to the add-in settings
  • Emails remain encrypted without private key
Most mentioned
  • Many users struggle with installing or using the extension
  • Issues with emails remaining encrypted
  • Problems with compatibility on personal devices and Macs
View all user reviews
Risk impact

Microsoft S/MIME is risky to use as it requires a number of sensitive permissions that can potentially harm your browser and steal your data. Exercise caution when installing this add-on. Review carefully before installing. We recommend that you only install Microsoft S/MIME if you trust the publisher.

Risk likelihood

Microsoft S/MIME has earned a fairly good reputation and likely can be trusted.

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