The remote host is using ReadNotify to track when and where emails are read.
The remote host is using ReadNotify to track when and where emails are read. This technology embeds a tiny link within an email. When the recipient opens the email, the link is retrieved from a ReadNotify server and the original sender is notified when the email was read as well as the IP address of the recipient. This is done without the knowledge of the recipient. In the case of ReadNotify, the recipient is presented with a dialogue asking if they would like to send the sender a notification that they have received the email. Even if the user clicks 'No' or 'Cancel', the sender is still notified, regardless of the recipients wishes.
Ensure that such activity is allowed by corporate policies and guidelines.