Do you use Microsoft Outlook to send supposedly-encrypted S/MIME email messages? If so, for at least last 6 months, your messages have been sent in both encrypted and unencrypted forms, exposing all your secret and sensitive communications to potential eavesdroppers.
If you are using Microsoft Outlook, you need to read an article in The Hacker News at http://bit.ly/2gbfpvW before you send your next message!
Comment: There are several better, more secure email programs than Microsoft Outlook. If you have a need for email security, you should investigate other solutions! You might start by looking at past articles about encrypted email services that have published in this blog. Start at: http://bit.ly/2gafXCb.