Secure email messages by using a digital signature

By digitally signing an email message, you apply your unique digital mark to the message. The digital signature (digital signature: An electronic, encryption-based, secure stamp of authentication on a macro or document. This signature confirms that the macro or document originated from the signer and has not been altered.) includes your certificate (certificate: A digital means of proving your identity. When you send a digitally signed message you are sending your certificate and public key. Certificates are issued by a certification authority, and like a driver's license, can expire or be revoked.) and public key (public key: The key a sender gives to a recipient so that the recipient can verify the sender's signature and confirm that the message was not altered. Recipients also use the public key to encrypt (lock) email messages to the sender.), which originate from your digital ID (digital ID: Contains a private key that stays on the sender's computer and a certificate (with a public key). The certificate is sent with digitally signed messages. Recipients save the certificate and use the public key to encrypt messages to the sender.). A digitally signed message proves to the recipient that you, not an imposter, signed the contents of the message, and that the contents haven’t been altered in transit. For additional privacy, you can also encrypt email messages.


Digitally sign a single message

  1. In the message, on the Options tab, in the Permission group, click Sign Message.

ShowI don't see Sign Message

  1. In the message, on the Options tab, in the More Options group, click the Options Dialog Box Launcher Dialog Box Launcher in the lower corner.
  2. Click Security Settings, and then select the Add digital signature to this message check box.
  3. Click OK, and then click Close.

If the Sign Message button isn’t visible, you might not have a digital ID configured to digitally sign messages.

  1. Compose your message, and then send it.

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Digitally sign all messages

  1. Click the File tab.
  2. Click Options.
  3. Click Trust Center.
  4. Click Trust Center Settings.
  5. On the E-mail Security tab, under Encrypted Mail, select the Add digital signature to outgoing messages check box.
  6. If available, you can select one of the following options:
  7. To change additional settings, such as choosing between multiple certificates to use, click Settings.
  8. Click OK on each open dialog box.

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Applies to:
Outlook 2010