<https://forums.slipstick.com/threads/90460-linking-contacts-to-a-message-where-the-contact-isnt-an-addressee/>
<http://schema.org/headline>
"Linking Contacts to a Message Where the Contact isn't an Addressee"
<https://forums.slipstick.com/threads/90460-linking-contacts-to-a-message-where-the-contact-isnt-an-addressee/>