Jumping Mouse a écrit : > Thanks again mouss. > > most of my users are in an office network behind a firewall and are > using an ms server 2003 dns for local lookups my isp's dns server for > non local lookups. My ISP is also hosting the dns records for the > postfix server. > > How can I test if postfix is getting an NXDOMAIN quickly? >
You can resolve the IP of their firewall, by executing (on the postfix box): host 1.2.3.4 where 1.2.3.4 is the firewall IP. if this returns a name, say joe.example.com, then resolve this name: host joe.example.com but if the IP and the name never change, the results are cached and the delay should only be noticed when the cache expires. one thing to do is to connect from one of your users machines using telnet: telnet smtp.example.org 25 and see if you get the banner quickly or not. (replace smtp.example.org with the name of your postfix, that is, the name that your users configured in their MUA). when doing so, sniff traffic on yor postfix box: tcpdump -n port 25 and host joe.example.com so that you see when postfix starts getting traffic. Other things to look at are: anti-virus on the client machine. firewall or proxy in the path. ... etc. Also take a look at the DEBUG README.
