Send a digitally signed or encrypted message

A digital signature on an e-mail message helps the recipient verify that you are the authentic sender and not an impostor. Encryption of a message scrambles the message text so that only your intended recipients can read it.

To use digital signatures and encryption, both the sender and recipient must have a mail application that supports the S/MIME standard. Outlook supports the S/MIME standard.

Do any of the following:

Send a digitally signed message

  Before you start this procedure, you must first have a certificate added to the keychain on your computer. For information about how to request a digital certificate from a certification authority, see Mac Help.

  1. On the Tools menu, click Accounts.

  2. Click the account that you want to send a digitally signed message from, click Advanced, and then click the Security tab.

  3. Under Digital signing, on the Certificate pop-up menu, click the certificate that you want to use.

    Note   The Certificate pop-up menu only displays certificates that are valid for digital signing or encryption that you have already added to the keychain for your Mac OS X user account. To learn more about how to add certificates to a keychain, see Mac OS Help.

  4. Do any of the following:

To

Do this

Make sure that your digitally signed messages can be opened by all recipients, even if they do not have an S/MIME  mail application and can't verify the certificate

Select the Send digitally signed messages as clear text check box.

Allow your recipients to send encrypted messages to you

Make sure that you have selected your signing and encryption certificates on this screen, and then select the Include my certificates in signed messages check box.

  1. Click OK, and then close the Accounts dialog box.

  2. In an e-mail message, on the Options tab, click Security, and then click Digitally Sign Message.

    Options tab, group 4

  3. Finish composing your message, and then click Send.

Send an encrypted message

  Before you start this procedure, you must first have a certificate added to the keychain on your computer. For information about how to request a digital certificate from a certification authority, see Mac Help. You must also have a copy of each recipient's certificate saved with the contacts' entries in Outlook. For information about how to add your contacts' certificates to Outlook, see Add a sender's certificate to the Address Book. Or, if your recipient is listed on an LDAP directory service, such as the global address list (GAL) with Microsoft Exchange Server, the recipient's certificate is published to the directory service and available to you together with other contact information.Or, if your recipient is listed on an LDAP directory service, the recipient's certificate is published to the directory service and available to you together with other contact information.

  1. On the Tools menu, click Accounts.

  2. Click the account that you want to send an encrypted message from, click Advanced, and then click the Security tab.

  3. Under Encryption, on the Certificate pop-up menu, click the certificate that you want to use.

    Note   The Certificate pop-up menu only displays certificates that are valid for digital signing or encryption that you have already added to the keychain for your Mac OS X user account. To learn more about how to add certificates to a keychain, see Mac OS Help.

  4. Click OK, and then close the Accounts dialog box.

  5. In an e-mail message, on the Options tab, click Security, and then click Encrypt Message.

    Options tab, group 4

  6. Finish composing your message, and then click Send.

    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.

See also

About digital signing, encryption, and smart cards

About security in Outlook

Applies To: Outlook for Mac 2011



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