Being under the SMTP section i assumed this was related to outgoing email.
Hi dda,
No, it's working in both ways.
I'm using these settings everyday.
"The purpose of the SMTP proxy is to control and optimise the SMTP traffic and to protect the local networks from threats when using the SMTP protocol. SMTP is used whenever an e-mail is sent from a local e-mail client to a remote mail server, that is, for the outgoing e-mails. It will also be used if an mail server is running on the LAN (i.e., within the GREEN zone) or DMZ (ORANGE zone) and the e-mails can be sent from outside the local network (incoming requests) through t hat mail server, that is, when clients are allowed to send e-mails from the RED interface."
http://docs.endian.com/3.2/utm/proxy/smtp.html