I use a Mozilla Thunderbird (email client) extension that performs client-side Sender Policy Framework (SPF) verification of my received e-mail messages. It has worked great. In July, I replaced my Linksys BEFVP41 with a Linksys RT31P2 because of my new usage of Vonage services. The only difference between the two devices is one acts as a VPN server and the other acts as a voice terminal adapter. All data network routing functions and configuration are the same. Since that time, the SPF verification has not worked from my home. I can take my laptop to any other public network, and the SPF verification works. The only thing that I can deduce is that the Linksys RT31P2 is blocking port 53/tcp, which is how SPF communicates with public DNS servers. However, I cannot validate this deduction. Has anyone experienced the same or similiar problem? Is there a way to validate the port 53/tcp blocking? Thanks in advance for your help.