Host lookup failure with Sendmail
 

hi,

I have a problem with sending mail from my fileserver (named Arkiv, for LAN access only) to my mailserver (named Post, in a DMZ). I basically only want to do this to aggregate my logcheck, etc mails in one mailbox, that is also accessible from the outside.

The fileserver is separated from the mailserver by a firewall where only sendmail connections orginating from the fileserver are allowed through (as well as ssh). The fileserver is not allowed any direct contact with the Internet.

Sending mail locally between users on the fileserver works fine and when I try to "telnet post 25" to the mailserver I can manually send mail through.

The problems start when I try to send an mail in any other way between the boxes. I then get the message accepted for delivery but then the host name resolve fails for some reason.

In var/log/maillog the attemted mail submission looks like this:

Sep 29 12:18:43 arkiv sendmail[26048]: i8TAGgrX026048: from=<root@arkiv.comba-telecom.se>, size=243, class=0, nrcpts=1, msgid=<Pine.LNX.4.58.0409291216310.26047@arkiv.comba-telecom.se>, proto=ESMTP, relay=root@localhost

Sep 29 12:18:43 arkiv sm-mta[26051]: i8TAIh3h026051: from=<root@arkiv.comba-telecom.se>, size=436, class=0, nrcpts=1, msgid=<Pine.LNX.4.58.0409291216310.26047@arkiv.comba-telecom.se>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]

Sep 29 12:18:43 arkiv sm-mta[26053]: i8TAIh3h026051: to=<mattias@post.comba-telecom.se>, ctladdr=<root@arkiv.comba-telecom.se> (0/0), delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=30436, relay=post.comba-telecom.se., dsn=4.0.0, stat=Deferred: Name server: post.comba-telecom.se.: host name lookup failure

Sep 29 12:18:43 arkiv sendmail[26050]: i8TAGgrX026048: to=<mattias@post>, ctladdr=<root@arkiv.comba-telecom.se> (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30243, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (i8TAIh3h026051 Message accepted for delivery)

Since I use my ISPs DNS, I have used /etc/hosts as a DNS for my system so far with no problem. I have not run into problems with resolving the relationship with Arkiv and Post before.

The /etc/hosts file looks like this

# For loopbacking.
127.0.0.1 localhost
192.168.11.101 arkiv.comba-telecom.se arkiv
192.168.12.2 post.comba-telecom.se post
192.168.1.1 grind.comba-telecom.se grind
# End of hosts.


I'm using the standard sendmail.cf and submit.cf on a Slackware 9.1 platform.

Any help is appreciated.

regards,
Mattias

Looks like you need a MX entry for your mail server as long as you use ISP DNS it won't work sorry.

Take a look at this and see if it helps you:

http://davespicks.com/writing/progra...upfailure.html

In particular, run that dig command on your arkiv system and see what it turns up.

Oh, and as the author says, his mailertable fix only solves the problem locally, but that might be all you need.

-Bill

Thanks for the help!

It solved the problem. Although it takes sometime for the mailsubmission to go through (approx 30s). I'm assuming it tries to resolve for an MX record before giving up and submitting anyway...

Is this to be the way to get sendmail to work between computers on a network without having to set up a fully fledged DNS service with MX records, etc. Or is there an alternative solution?

/mattias

Should this mailertable contain the host I am using? or the host that keeps bouncing mail back with Hostname lookup failure? I have about 6 ip's that bounce mail back with either hostname lookup failure, or Timeout exceeded. All other ip's can send mail just fine. I use sendmail on slackware 12.2 and earthlink and netcom.com as well as mindspring.com keep bouncing my mail back with these errors. I run through a motorola router (DSL) and just can't seem to figure out how to send email to these certain ip's. They can send email into me, but I can't send to them. Is there anything I can do to fix this?