troubleshooting Question

I can neither send nor receive emails

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HGunther asked on
8 Comments1 Solution391 ViewsLast Modified:
In firewall, only allow packets with target port = 25, 80, 110, 443(HTTPS), 576(submition) and 8080(Tomcat) to come in. DNS is pointed to 3 outside servers; OS is Linux 7.2. The firewall is put outside the router. Now I can neither send nor receive emails. I found that this server can not resolve domain name, so I cannot find any host by nslookup. That's why? Can you tell me which ports shall be opened for incoming when a program needs to access DNS?

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