Information about "Request S/MIME receipt for this message" option in Microsoft Outlook for Windows when sending digitally-signed emails


Explanation

This option allows you to verify that your digital signature is being validated by recipients. It also requests confirmation that the message was received unaltered and notifies you who opened the message and when it was opened.

When you send a message with an S/MIME return receipt request, this verification information is returned as a message sent to your Inbox.