Apple Mail unable to verify S/MIME CERTIFICATE

Asked By 0 points N/A Posted on -


I have problems with my Apple mail. It could not verify my message signature. The error says: MAIL WAS UNABLE TO VERIFY THE AUTHENTICITY OF THE S/MIME CERTIFICATE PROVIDED BY [email protected] (which is the user). MESSAGES SIGNED BY THIS USER MAY BE COMING FROM A DIFFERENT SOURCE. Please advice on what to do. Is it alright to click the OK button?

Verify Signature

Unable to verify message signature

Mail was unable to verify the authenticity of the S/MIME certificate provided by " @MIT.EDU". Messages signed by this user may be coming from a different source.

Answered By 0 points N/A #121109

Apple Mail unable to verify S/MIME CERTIFICATE


The simple answer is that this happens if the person sending you mail has signed their message with a personal certificate, that is not trusted by your computer.

You need to contact that person who sent the message signed mistakenly, and insist them on not to sign their mails while sending. The people who usually have these kind of signing certificates installed on their computer, their Mail app has two extra icons while a message is being composed, next to the right of ‘Signature’ menu. The first icon looks like a padlock and the second icon looks like a star-burst circle.

When they want the Mail app to digitally sign messages, the star-burst circle will have a small "tick" in the center of the circle:

For them to stop signing mails, they need to click the star-burst circle, so that it has an ‘X’ in the center: 

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