UAG5100 User’s Guide
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SMTP Redirect
18.1 Overview
SMTP redirect forwards the authenticated client’s SMTP message to a SMTP server, that handles all
outgoing e-mail messages. In the following example, SMTP server A is connected to the lan2
interface in the LAN2 zone. When a client connected to the lan1 interface in the LAN1 zone logs
into the UAG and wants to send an e-mail, its SMTP message is redirected to SMTP server A. SMTP
server A then sends it to a mail server, where the message will be delivered to the recipient.
The UAG forwards SMTP traffic using TCP port 25.
Figure 126
SMTP Redirect Example
18.1.1 What You Can Do in this Chapter
Use the SMTP Redirect screens (see
) to display and edit the SMTP
redirect rules.
18.1.2 What You Need to Know
SMTP
Simple Mail Transfer Protocol (SMTP) is the Internet’s message transport standard. It controls the
sending of e-mail messages between servers. E-mail clients (also called e-mail applications) then
use mail server protocols such as POP (Post Office Protocol) or IMAP (Internet Message Access
Protocol) to retrieve e-mail. E-mail clients also generally use SMTP to send messages to a mail
