• Correct setup of the e-mail client Apple macOS - Mail
• Correct integration of the Certification authorities into the operating system.
• Valid digital User certificate integrated into the operating system.

No further configuration is required for the Mail application, you can now sign any e-mail. If you have the public key of your communication partner, you can also encrypt any e-mail.

• Click on the “New e-mail” icon in the Mail application and compose the e-mail.
• Before sending, check that the message is digitally signed: the button “Digitally sign message” at the top right of the subject line appears activated in blue.
• As soon as you click on “Send”, the e-mail will be digitally signed and then sent.
  • You may be asked to enter your local user name and password once more.
• The communication partner will see the loop symbol as a sign of a digitally signed e-mail.

To encrypt, you must first have the communication partner's public key. To do this, have your communication partner send you a digitally signed e-mail, for example, which is automatically added to your key ring.

• Click on the “New e-mail” icon in the Mail application and compose it.
• Before sending, check that the message is digitally encrypted: the button “Digitally encrypt message” at the top right of the subject line appears activated in blue.
• As soon as you click on “Send”, the e-mail will be encrypted and then sent.
  • You may be asked to enter your local user name and password once more.
• The communication partner sees the lock symbol as a sign of an encrypted e-mail.