My question is how to enable SMIME sign and encryption for standard email account (imap/smtp)?

I want to automatically sign all out email messages and ecryption if possible for specified percipients.

I have a couple of trusted certs with private keys packed into pks7 and p12 containers. And off course public keys for all recipients.

I was easily solve this issue for OSX Mail.app and iOS Mail application, but I don't understand how it works and how to configure it on the Windows 10 and mobile Windows Phone - in the builtin mail clients.

In ideal I want the same behavior like in the iOS's Mail app. It's really easy to understand for my parents.

Please suggest any solution how I can configure it.


To my ongoing aggravation, it appears to not currently be possible to use S/MIME with WP8.1 or W10M unless you are using an Exchange ActiveSync-based account. Secure email on IMAP and POP3 accounts is not supported, for some reason. From the user's perspective, this is a completely pointless and artificial restriction - other platforms' email clients have no such limitation, including Outlook on PCs - but I'm sure Microsoft thought they had a good reason.

You should go into Microsoft's Insider Hub / Feedback apps (any possibly also relevant UserVoice sites you can find, but it looks like those have been shut down for Windows Phone) and upvote the (many) suggestions requesting S/MIME support for non-Exchange email accounts.

The following instructions cover enabling S/MIME on Windows 10 Mobile (W10M), using the current Insider Fast build. Older versions of the OS may have different steps (you need to have at least Windows Phone 8.1 Update, I think). If you connect to an Exchange server (usually means a school or business email address), you should be able to make S/MIME work on the phone. Even without that, the option is probably present (but disabled):

  1. Open the email client (Outlook Mail on W10M).
  2. Tap the three dots in the lower right to show the application menu.
  3. Tap on Settings to open it. (For WP8.1, this is roughly the same as going to the Settings hub, swiping to the Applications pivot, and choosing Mail, I think).
  4. Tap on Email security.
  5. Select an account at the top (only accounts using ActiveSync will be available).
  6. Turn on "Always sign with S/MIME" and/or "Always encrypt with S/MIME", as you please.
  7. Leaving the certificate selection on "Automatically" should be fine, but if you tap "Manually" you can see, in the new drop-down that appears, what certificates the phone knows about that could be used.
  8. Once you've made your desired changes, use the Back button to exit back to the email client.

To check if it's working, do the following:

  1. Create a new email (or reply to / forward one) using the relevant account.
  2. If the mail is signed, a little ribbon outline should appear on the right side of the Subject line. If the mail is encrypted, a little padlock icon should appear in the same area.
  3. To toggle encryption or signing, tap the three dots in the lower-right to display the message composer menu.
  4. Tap on Options, then on Sign and/or Encrypt to toggle those options.
  5. Hit Back or tap on the three dots again to close the menu.

You can configure it by going into the setting and you should follow all the instructions that are been given.

  • 3
    you should follow all the instructions that are been given. Can you please list the instructions here. For example, Step 1-Go to settings, step 2-click on this tab, etc...
    – Kolappan N
    Jun 8 '16 at 16:11
  • 1
    This is not even slightly an answer. You don't specify what settings, how to get to them, where the instructions to be followed may be found, any steps you think may have been missed, or anything else useful. To whoever up-voted this, please reconsider. This kind of non-answer should not be promoted.
    – CBHacking
    Jul 14 '16 at 1:08

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