Once you have completed setting up your Digital Encryption Certificate, and you have also saved a copy of your intended recipients public certificate, you are now ready to send encrypted email.
In Outlook, click New E-mail to create the new email message.
Start typing the email address of your recipient. If this email address shows as an auto-complete recommendation, delete the recommendation. (Deleting the auto-complete is necessary, so that Outlook knows to look for the certificate information for this user)
Click on the Options tab in Outlook.
Select 'Encrypt' and 'Sign' on the Options tab.
Finish composing your e-mail message. Note that the subject line will not be encrypted, only the message body will be encrypted.
If Outlook gives any warning messages about encryption, cancel the message, or it will be sent without encryption. Test your email encryption by sending yourself an encrypted email, and if this works, check to make sure you have a Contact item for the recipient in Outlook that also has the recipient Public Key.