Knowledge Base

Encrypting an email message protects its privacy. S/MIME allows you to encrypt email content using the recipient's public key, so only the intended recipient with the matching private key can read the message.

A digital signature on an e-mail message helps the recipient verify that you are an authentic sender and not an impostor. To use digital signatures, the sender and recipient must have a mail application supporting the same encryption type.

Send a digitally signed message

Before you follow the steps below, your S/MIME certificate must be added to the keychain on your computer.

1. Click on Outlook and select Preferences.
2. Choose the account from which you want to send an encrypted message and select Security.
3. In Certificate, select the certificate that you want to use. You will see the certificates which have been added to the keychain for your Mac OSX user account that is valid for digital signing or encryption.
4. Select either of the following:
   1. Send digitally signed messages as clear text
      This option ensures that your digitally signed messages can be opened by all recipients, even if they do not have an S/MIME mail application and cannot verify the certificate.
   2. Include my certificates in signed messages
      If you want to allow your recipients to send encrypted messages to you, make sure that you have selected your signing and encryption certificates.
5. Click on OK, and close the Accounts dialog box.
6. When compiling your email, in the message box, click on See more items (the little three dots) and select S/MIME > Add digital signature.

Send an encrypted message using S/MIME

You must have a few things in order before you can follow the instructions:

• Your S/MIME certificate needs to be added to the keychain on your computer.
• You must have a copy of each recipient’s certificate saved in Outlook.

1. Click on Outlook and select Preferences.
2. Choose the account from which you want to send an encrypted message and, select Security.
3. In Certificate, select the certificate that you want to use. You will see the certificates which have been added to the keychain for your Mac OSX user account that is valid for digital signing or encryption.
4. Click on OK, and close the Accounts dialog box.
5. When compiling your email, in the message box, click on See more items (three dots) and select S/MIME > Encrypt with S/MIME.

Note: When you send an encrypted message, your recipient's certificate is used to encrypt his or her copy of the message. Your certificate is used to encrypt the copy that is saved to your Sent Items or Drafts folder in Outlook.