How do I remove a s/mime certificate for a contact in iOS7 mail.app?

I'm using s/mime for two-way encrypted emails with several colleagues. A new colleague tried to install s/mime in Outlook for Windows and he sent me a signed email which I opened in iOS and trusted the certificate.

Then he changed his mind and stopped using s/mime (trouble with Outlook). iOS still tries to encrypt the email messages I send to him so he sees blank messages. I can find no way to list the certificates I have trusted for my contacts so I can remove this certificate.

Where do I have to look?

  • for those who follow: the only solution i found was a clean install of iOS. When I got a new phone, i created it as a new device rather than restoring my old phone to it.
    – Steve
    Nov 1, 2014 at 7:49

2 Answers 2


You should be able to view and remove certificates or S/Mime if you go to:

  1. Mail, Contacts and Calender
  2. Go to your mail account
  3. Click advanced
  4. Uncheck S/Mime or remove the certificate

Please also check out this Official Apple Guide By clicking the name in the Mail.App you should be able to revoke the certificate.

Check this image:

Don't trust

  • that would remove my personal certificate, which would break the encryption to my other colleagues. I just want to remove a single contact's certificate, which I "trusted" by tapping their name in an incoming email and then tapping "Trust" on the certificate.
    – Steve
    Feb 11, 2014 at 8:44
  • @Steve please check the edit
    – Rob
    Feb 11, 2014 at 9:18
  • My problem is that I cannot get to there: because he has stopped sending signed emails, when I tap on his name I get his address book contact card (both from an existing email received from him, and when creating a new email to send). Is there another way to get to the place you show in your image? I'm using iOS7. Your image looks to be from an older version?
    – Steve
    Feb 13, 2014 at 3:14

Note: Although this is an iOS 7 question, it is still valid for iOS 11.

  1. Re-open the signed email he had sent you (or any other email sent with that certificate)
  2. Click on the sender address
  3. Select "View certificate"
  4. The certificate should be displayed with an option to uninstall it

Once uninstalled, new emails to this sender won't be encrypted any more.

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