ZyXEL UAG4100 User Guide - Page 236

Chapter 17 SMTP Redirect 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, Security Policy and Policy Route With SMTP redirect, the relevant packet flow for SMTP traffic is: 1 Security Policy 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 security policy(ies) 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 Figure 153 on page 235 work, make sure you have the following settings. For SMTP traffic between lan1 and lan2: • a from LAN1 to LAN2 security policy 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 security policy (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. 17.2 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. UAG Series User's Guide 236