Port 25 test succeeds but sending does not work

Question: I performed the port 25 test and it succeeded. Why do I get an error that a domain could not be resolved?

Brief Answer: Use another DNS server that works correctly. Give your ISP a call for details.

Answer: This usually happens when you use an incorrect DNS server or an IP address of a host that is not a DNS server at all. The program may detect automatically a private DNS server that does not contain all names of the Internet. Manually you may enter an IP address of a host that does not run a DNS service. This usually causes Email Security to raise an exception that a domain could not be resolved. You can easily check if the DNS server that appears in Email Security is correct by using the nslookup command. Press the Start button then select the Run command then enter nslookup into the Open field then click the Ok button. After that you will see an IP address of your default DNS server. Enter different domains such as hotmail.com yahoo.com you have on your email list in the command prompt and check if they can be resolved by the DNS server. If everything works well here, you should check if you use the same DNS server (check it by IP addresses) in Email Security. Change the IP address of DNS server manually if the addresses are different. Use the DNS server you saw in the nslookup for Email Security only if it resolves your domains correctly.

If you are having difficulties with defining your correct DNS server, give your ISP a call and ask them about DNS server you can use for a SMTP server you run on your PC locally.

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