Jean-Francois Bilodeau wrote: > I run a mail server using a static IP, but for a while, GMail would > refuse any messages from my server, saying that it was a dynamic IP. > I've enabled SPF on my DNS server, and that seemed to fix the problem. > However, I'm curious to know how a server can know if an IP is static or > dynamic. How can you find out? > > Thanks, > > J-F > I believe that large mail servers and and black hole websites maintain lists of what they believe to be ranges of dynamic ip's and filter based on those lists. The lists can be wrong and so you can be penalised for that. Another test which many spam filters will perform is reverse dns look up and if the domain name returned for the ip of the contacting host does not match the info provided in the smtp HELO, it can increase your spam score. The way around this is for your ISP to either delegate your IP address to you and allow your private DNS server to resolve the reverse look ups, or configure its own DNS servers to provide your info for reverse lookups of your IP address. Old Magma delegated my IP address to me, teksavvy on behalf of NCF does reverse lookups for me now. J-F, the headers in your mail message report your ip as (pppoe-static-209-91-177-178.vianet.ca [209.91.177.178]), and you would rather be something like mail.chronogears.com [209.91.177.178]). Getting mail through from little sites like ours can be a painful process. Michael