Microsoft Outlook can also send encrypted e-mail messages, but instead of using SSL, it relies on a system of public and private keys. The message is encrypted using your private key, and only recipients that have the associated public key will be able to view the e-mail. The public key can be shared with any recipient, whether they use Outlook or not.
Guidance on the Microsoft Office site explains, "Sending and viewing encrypted e-mail messages requires both sender and recipient to share their 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.], or public key certificate. This means you and the recipient each must send the other a digitally signed message, which enables you to add the other person's certificate to your Contacts. Once both parties have shared certificates, sending and viewing encrypted e-mail messages between them is the same as with any other e-mail messages."
After You Hit Send
The precautions described above will help ensure that prying eyes don't view or access the e-mail on your PC, and protect your messages from being intercepted en route, but what about protecting the privacy of your e-mail even after you send it? Perhaps you have something of a sensitive nature to communicate, and you want to make sure that the recipient doesn't forward or share the message.
Microsoft Outlook has information rights management (IRM) features that let you exercise some control over your messages even after you hit Send. When you are composing an e-mail in Outlook 2010, select Options on the menu bar, then click the arrow under Permission, and check the Do Not Forward option. Recipients who are not using an e-mail client that supports Microsoft's IRM must download the Rights Management Add-on for Internet Explorer to view restricted messages.
Some businesses manage the IRM features from their own servers, but for individuals or businesses that don't, Microsoft can manage IRM credentials and authentication for you. The first time that you use the IRM features, Microsoft will automatically prompt you to register to use the service (to see the IRM screen, click the thumbnail image below).
Selecting the Do Not Forward option for your e-mail message makes the message private between you and the intended recipient. It lets the recipient receive and view the e-mail, but it prevents the message from being forwarded, printed, or copied.