Sendmail problem.

[linux1]

Here is the error message I'm getting when I try to send a message.

RCPT TO <mrx@externalsite.com> failed: <mrx@externalsite.com>... Relaying denied. IP name lookup failed [192.168.1.216].

Here is my setup.

I have a linksys router connected to the public internet. My server (Box A) is running sendmail and is setup according to the linuxhomenetworking.com for an email server. Box A is connected to the router and it's domain is mysite.com.

Box B is running a desktop installation with evolution setup read and write e-mails. It is connected to the router and is setup according to the linuxhomenetworking.com for an email client.

When I send e-mail from Box B to an external e-mai address, I get the above error message. I'm trying to send mail to the external internet. I do not get the error message if I send e-mail to an account on Box A, for example, an e-mail to mrx@mysite.com works.

I figure I have a config problem on Box A. Can anyone help me out? Do you need more information about my configurations?

Cheers,
Jens.

[starfish]

Sounds like your /etc/hosts file may be incorrectly setup.
Your ISP isn't going to allow relaying from IP addresses in the RFC1918 space (ie. 192.168.x.x), so sendmail must be informing the mail relay server with the wrong IP address.

What does the /etc/hosts file look like. Follow the Sendmail troubleshooting steps , also take a look at this link for the correct configuration for /etc/hosts.
http://www.linuxhomenetworking.com/l...work-linux.htm
Start out with only an entry for your loopback interface, and you should be OK.

[linux1]

Hi starfish,

Thanks for the reply.

The problem goes away when I add externalsite.com to the access file in /etc/mail on the server machine. This isn't very useful as I'd have to add every site that I ever want to send e-mail to the access file. Here is some debug information. I've removed my real e-mail address to avoid harvesting.

This is the failure scenario. My domain is homeip.net and the local user name is mrx. I want to send mail to msx@externalsite.com. Hostname server is the sendmail server and bigdog is the client machine.

[mrx@bigdog etc]$ telnet server 25
Trying 192.168.1.2...
Connected to server (192.168.1.2).
Escape character is '^]'.
220 homeip.net ESMTP Sendmail 8.13.1/8.13.1; Thu, 17 Feb 2005 22:10:51 -0500
HELO homeip.net
250 homeip.net Hello [192.168.1.216], pleased to meet you
MAIL FROM:mrx@homeip.net
250 2.1.0 mrx@homeip.net... Sender ok
RCPT TO:msx@externalsite.com
550 5.7.1 msx@externalsite.com... Relaying denied. IP name lookup failed [192.168.1.216]
QUIT
221 2.0.0 homeip.net closing connection
Connection closed by foreign host.
[mrx@bigdog etc]$

The hosts file on server is:
127.0.0.1 server localhost.localdomain localhost

The hosts file on bigdog is:
127.0.0.1 localhost.localdomain bigdog localhost
192.168.1.2 server

Does ant of this help? Is there other output that I can help out with?

I can't imagine that I'm the only person that is trying to run a sendmail server behind a NAT and sending e-mail from a mahine that is not the server machine. I figured that this is a typical problem.

Thanks again for your help,
Cheers,
Jens.

[linux1]

Hi starfish,

I did some more experimenting and then I went back and re-read the section on the access file.

It turns out that I needed to add

192.168.1 RELAY

to the access file so that mail originating from mahines in the home network would be relayed. Is that the right thing to do?

Cheers,
Jens.

[starfish]

That's probably it,

I didn't realize the mail server was on the home network. I thought it was your ISP's mail server returning the error.

You should be OK.

[viket]

hi all.
i want to host a mail server in my corporate office but am unaware as to what all is to be done.
can anyone guide me on that.
regards,

[LinuxFreak]

Dear viket,
Hello,

http://www.linuxhomenetworking.com/l...n/sendmail.htm

Best Regards.