Chapter 18 SMTP Redirect
UAG5100 User’s Guide
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server. The older POP2 requires SMTP for sending messages while the newer POP3 can be used with
or without it. This is why many e-mail applications require you to specify both the SMTP server and
the POP or IMAP server (even though they may actually be the same server).
SMTP Redirect, Firewall and Policy Route
With SMTP redirect, the relevant packet flow for SMTP traffic is:
1
Firewall
2
SMTP Redirect
3
Policy Route
Even if you set a policy route to the same incoming interface and service as a SMTP redirect rule,
the UAG checks the SMTP redirect rules first and forwards SMTP traffic to a SMTP server if matched.
You need to make sure there is no firewall rule(s) blocking the SMTP traffic from the client to the
SMTP server.
You also need to manually configure a policy route to forward the SMTP traffic from the SMTP server
to the Internet. To make the example in
work, make sure you have the
following settings.
For SMTP traffic between lan1 and lan2:
• a from LAN1 to LAN2 firewall rule to allow SMTP messages from lan1 to lan2. Responses to this
request are allowed automatically.
• a SMTP redirect rule to forward SMTP traffic from lan1 to SMTP server A.
For SMTP traffic between lan2 and wan1:
• a from LAN2 to WAN firewall rule (default) to allow SMTP messages from lan2 to wan1.
Responses to these requests are allowed automatically.
• a policy route to forward SMTP messages from SMTP server A to the Internet.
18.2 The SMTP Redirect Screen
To configure redirection of a SMTP message to a SMTP server, click Configuration > Network >
SMTP Redirect. This screen displays the summary of the SMTP redirect rules.
Note: You can configure up to one SMTP redirect rule for each (incoming) interface.
