The message sent to the third-party recipient was received in the junk or spam folder.
Email Security.cloud
Outbound emails are scanned by the Email Security.cloud service and attempted to be delivered if the verdict is clean. We have no control over where the message lands on the recipient's side, if this is junk, spam, or any other folder, as this is done by the recipient's mail server.
Contact the recipient should further information about redirection to the junk folder be needed. Technical support can provide the delivery logs on your request.