Canon DU7-1178-000, Service Manual, Page: 60 / 122

Chapter 2
2-8
Encrypted SMTP Reception
The iR 2270 and later models support SSL (TLS) encryption for receiving email messages from SMTP
servers. To use this feature, a valid server certificate is required. When SSL or On option is selected for
Allow SSL (SMTP Receive)* and the email server supports STARTTLS command, the imageRUNNER/
iR can communicate with encrypted packets using SSL (TLS). When Off option is selected for Allow SSL
(SMTP Receive) control, the imageRUNNER/iR does not include STARTTLS in a response for EHLO.
The communications slows down since not only the user name and password but also the entire data for
email sending are encrypted. When Off option is selected for Allow SSL (SMTP Receive) or the email
server does not support STARTTLS command of SMTP protocol, the communication packets are not en-
crypted.
*Allow SSL (SMTP Receive) control: is displayed by selecting Additional Functions > System Settings
> Network Settings > Email/I-Fax > Authent./ Encryption.
STARTTLS Command
An extended SMTP command that notifies a start of encrypted communications in SSL/TLS to the SMTP
server, defined in RFC 2487.
The following lines exemplify communications when STLS is enabled.
...
S: 220 mail.imc.org SMTP service ready
C: EHLO mail.example.com
S: 250-mail.imc.org offers a warm hug of welcome
S: 250-STARTTLS :<-- Indicates the server supports STARTTLS.
S: 250 DSN
C: STARTTLS : <--Declares the use of SSL/TLS.
S: 220 Go ahead
C: <starts TLS negotiation>
C & S: <negotiate a TLS session>
C & S: <check result of negotiation>
-- The communication packets are encrypted from now on --
C: EHLO mail.example.com
S: 250-mail.imc.org touches your hand gently for a moment
S: 250 DSN
C: MAIL FROM <ifax@mail.example.com>
S: 250 Sender OK
...
The client is notified with the response of EHLO that the server supports STARTTLS. When the client
issues STARTTLS command, the server and client perform TLS negotiation and resume communications
from the beginning with encrypted packet data.
If SSL option is selected for Allow SSL (SMTP Receive) control and the client carry on communicating
in plain text, without using STARTTLS, the imageRUNNER/iR replies "530 Must issue a STARTTLS
command first" of SMTP mail command and terminates the SMTP connection with the error. The user
interface indicates "SSL Error (SMTP RX Reject)" in the status line.
If On option is selected for Allow SSL (SMTP Receive) control, the imageRUNNER/iR accepts commu-
nications with the client in plain text, without using STARTTLS. If an SSL processing results in an error,
for example the imageRUNNER/iR does not feature an encryption algorithm common to the client, the
user interface indicates "SSL Error (SMTP Receive)" and terminates the SMTP connection with the error.
Allow SSL (SMTP Receive) control defaults to Off.