From: Byron L.Hicks (no email)
Date: Thu Aug 19 2004 - 08:58:44 EDT
> If I understand you correctly, you are saying that these sites are
> not able
> to send mail to you. Assuming that they are diverse sites that don't
> significant similarities, this suggests that the problem is on your
In theory, I agree. But I'm running out of options in my
troubleshooting and I'm looking for some wisdom from some of the
>> From these sites, I
>> can't connect to our mail server, on other sites, I can.
> I don't understand what this is supposed to mean. It's their mail
> that are supposed to try to connect to your mail server.
I understand that. I have unix account access at one of the sites that
cannot connect to our mail servers. I have sent test email, and I have
tried to telnet to port 25 on the mail server, and the connection times
out. I have put a Finisar network analyzer on the ethernet port of our
border router, and I don't see the traffic even crossing the router.
We have no firewall, and the access-list is right on the router (we are
receiving mail from other sites). What else can I look at?
> When you say you can't connect to your server on port 25, where
> exactly are
> you trying from?
I have a unix account on a server at one of the remote sites that
cannot send email to NMSU.
> Did you try emailing (or calling) the administrators of
> those sites?
They just point to me and say "The problem is on your end, fix it."
Much like you are saying in this email.
> If you use SPF, are your records valid? Do the senders get any
We aren't getting bounces from our mail server. Their mail servers are
bouncing the messages because the connection to our mail server timed
> Your statement of the problem is lack of specifics. We can't check
> your SPF
> records. We can't check if those domains have a common provider.
The domains in question do not have a common provider. We are not
> So all we
> can do is tell you to troubleshoot.
I understand that. Let me restate my request: If anyone on nanog
cannot send email to nmsu.edu, please send me a tcptraceroute on port
25 to our mail server. I need some forensics to help me diagnose this
problem. You will have to reply to me at to
keep the noise level down on the list. Thanks in advance for any help
that I will receive.
-- Byron L. Hicks Network Engineer NMSU ICT