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Secure email with S/MIME on macOS

These articles describe how to use S/MIME with the macOS Mail application.

Normal email is insecure. There is no way to prove who sent it or detect if it has been tampered with. Also, there is no way to ensure it cannot be read by other people.

Secure email addresses those problems. Secure emails can be signed to prove who sent it and to show if it has been modified since it was signed. Also, secure emails can be encrypted, so only the intended recipient can decrypt it.

Sending secure email takes a little bit of effort to set up, which is one of the reasons why most people don’t bother. But if you want to do it, these articles describe how to set up secure email with S/MIME on macOS.

Why use S/MIME?
Background on the benefits of secure email.
Obtaining credentials
Obtaining credentials for S/MIME.
Configuring keychains
Adding the credentials with the Keychain Access application.
Using macOS Mail for secure email
Sending and receiving secure emails with the Mail application.
Troubleshooting
Solving common problems.