The remote host is vulnerable to a Denial of Service (DoS) attack.
The remote host seems to be a Canon ImageRUNNER printer, running an SMTP service. It is possible to send an email to the remote service and it will print its content. An attacker may use this flaw to send an endless stream of emails to the remote device and cause a denial of service by using all the paper in printer.
Disable the email printing service using the web interface.