Encrypting Email With iOS Mail – A How-To


| How-To

Page 4 – Next: Multiple Email Addresses, Exchanging Certificates, Sending Encrypted Email

A “Gotcha” for Those With Multiple Email Addresses in the Same Account

If you’re using certificates for multiple email addresses within the same account, things get a bit hairy. You’ll need to choose each certificate at least once in the Settings > Mail > [Account] > Advanced > S/MIME sections for both Sign and Encrypt by Default. After each one, be sure to save changes by tapping Advanced > Account > Done, as above.

If you’re using certificates for multiple email addresses within the same account (multiple From: addresses), things get a bit hairy. You’ll need to choose each certificate at least once in the Settings > Mail > [Account] > Advanced > S/MIME sections for both Sign and Encrypt by Default. After each one, be sure to save changes by tapping Advanced > Account > Done, as above.

It seems that selecting the certificates here activates them for Mail to use for future signing and encrypting. Additionally, based on our tests, it doesn’t seem to matter which certificate is checked here, just so long as each of them has been checked at least once.

Exchange Certificates With Your Recipients

In order for encrypting email with iOS Mail to work, you have to exchange public certificates with your recipients. Simply send an email, asking for a reply back after your recipient has followed the same steps. Forward this article to your recipients so they can follow all of the required steps.

When you receive the reply from your recipient, there should be a blue check mark beside their email address, along with a tick. Now you need to install their public certificate on your iPhone or iPad. Tap the check mark or the email address to get to the next step in doing so.

A signed email in iOS Mail - encrypting email with iOS Mail

Tap the blue checkmark to get to your recipient’s public certificate

The next screen tells you the recipient signed the email with a trusted certificate. Tap on View Certificate to begin installing the public certificate into the iOS Keychain.

A screen in Mail showing the email is signed - sending encrypted email with iOS Mail

Tap on View Certificate

You’ll see the certificate on the next screen, with an option near the bottom to Install. Tap that menu item, then tap Done in the top right corner.

A certificate in iOS - encrypting email with iOS Mail

Tap Install to add the public key to your iOS Keychain

Make sure your recipient does this too. Your recipient won’t be able to open your encrypted email if they don’t.

Send Your First Encrypted Email

Now you should be able to send encrypted email with iOS Mail. Go into the Mail app, and compose a new message. After you’ve typed in your recipient’s email address or chosen it from the address book, tap in the To: field again. You should see a blue lock to the right, just beneath the Send button. Tap the unlocked blue lock. That tells Mail to send an encrypted email. Leave the lock alone if it is already locked.

Tapping the blue lock to encrypt an email - sending encrypted email with iOS Mail

Tap on the blue lock to tell Mail to encrypt the email

Now, go ahead and type out your email, and tap Send. Mail will send your encrypted email. Nobody will be able to read it without your public key.

12 Comments Add a comment

  1. @Jeff Butts: Thanks for the tip. 1) the instructions that you linked to suggest putting the cert in the System keychain, and 2) exporting from the Login keychain also does not allow p12 export.

  2. Oh, I see how to do it. 1) it does have to be in the Login keychain, 2) select the My Certificates category, and 3) twist down the triangle next to the certificate and select the key inside the certificate. That will export a p12 file. Oddly, once I’ve done this I can export directly from the certificate too.

  3. Scott B in DC

    Nice article for the geeks, but this highlights what is wrong with the system: could I get my father to follow along in order to send private messages in email?

    Until someone comes up with a way for anyone to use encrypted email without having a computer science degree, it’s a kludge.

    (I know… my inner curmudgeon is showing)

  4. Many thanks for this article. It’s a great help for those of us who need to set up encrypted mail on iOS and can’t use Apple’s Configurator 2 utility to do it.

    @khurt: The procedure described in the article above isn’t “doing it wrong”. It’s currently the only way that makes it possible to set up encrypted mail in iOS for anyone who is using anything other than macOS 10.12.2.

    In my case, I’m in the middle of a project on my Mac Pro (running Yosemite 10.10.5) that will extend to December. Alas, thanks to the tyranny of the App Store, there is no version of Configurator available that will run in Yosemite. Configurator 2 is all that is available, and it runs only on macOS 10.12.2.

    I have hundreds of apps and plugins, and disrupting my workflow with a new system installation in the middle of a project would be an idiotic move. No thanks. This article made it possible for me to set up encrypted mail on my iPad, despite Apple’s refusal to provide a version of Configurator that will work with a version of OS X that is (nominally) still supported.

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