UNIX for Dummies Questions & Answers

Hi,

Our mail server is running red hat 5.1 and qmail. It has 2 network cards in it to form two separate networks, both requiring mail. As of yesterday all the users on one of the network interfaces can no longer send email, they can however receive. All users on the other interface are unaffected and can do as they please.

I am a linux/unix newbie so am not realy sure what to do, can anyone suggest anything? I have rebooted it to no avail. I have also ruled out the cabling and connecting switches (3com) by connecting a machine direct and attempting to telnet to port 25, which doesn't work.

Nothing has changed anywhere else on the network. I guess I just need to get port 25 back on the second ethernet card, although I don't understand why it has disappeared. It's quite an old machine with 95% disk usage.

Any advice, no matter how simple, is greatly received.

Cheers.

it seems like your smtp server isnt running, and that routing is fine since you said they can recieve their mail. that 95% disk usage though unrelated should be taken care of. some drives even degrade in performance once you go above 90% usage. so ensure that your smtp server is still running.

Thanks, but the users connected to the other network card in the same machine can send and receive, so surely smtp is running? Or can it be started individually for each ethernet card?

Cheers

I'm not quite sure if Redhat 5.1 had the ability yet (yeesh... that's the oldest production Redhat box I've ever heard of - I hope it being patched), but xinetd can bind to an interface, as opposed to listening on all at once. Are you using inted or xinetd? Or either, for that matter? Was anything changed, upgraded, edited, or added in the past few days?

Not sure if this will help but Sendmail doesn't need to be running to send email - only to receive.

Since the problem isn't that the folks can't receive, only send, then the process for qmail is probably there and working (with the assumption that qmail works the way sendmail does).

Thanks for the help, but I've worked it out. The pcs on the second network card have internal IP addresses within a range that the mail server doesn't understand. So each time they were trying to send an email it was doing a reverse lookup on their IP, although the name server appears to have gone down and has been down since the problem started. All the other users on the other network card have public IPs which it knows about and doesn't need to look up.