I'm pretty much a linux noob.. been using it for years, but never very in depth. I'm trying to set up sendmail to send me an email from my linux box to my email account on my isp (tampabay roadrunner). I have my linux box /etc/hosts file set up with a line that looks something like this:

127.0.0.1 blah blah
192.168.1.xxx server.mydomain.com server

My emails using sendmail are being bounced back with this error:

From MAILER-DAEMON@server.mydomain.com Wed Mar 10 09:23:23 2004
Return-Path: <MAILER-DAEMON@server.mydomain.com>
Received: from localhost (localhost)
by server.mydomain.com (8.12.10/8.12.10) id i2AENNDk002134;
Wed, 10 Mar 2004 09:23:23 -0500
Date: Wed, 10 Mar 2004 09:23:23 -0500
From: Mail Delivery Subsystem <MAILER-DAEMON@server.mydomain.com>
Message-Id: <200403101423.i2AENNDk002134@server.mydomain.com>
To: <root@server.mydomain.com>
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
boundary="i2AENNDk002134.1078928603/server.mydomain.com"
Subject: Returned mail: see transcript for details
Auto-Submitted: auto-generated (failure)

This is a MIME-encapsulated message

--i2AENNDk002134.1078928603/server.mydomain.com

The original message was received at Wed, 10 Mar 2004 09:23:23 -0500
from localhost.localdomain [127.0.0.1]

----- The following addresses had permanent fatal errors -----
<edited@emailaddress.com>
(reason: 550 5.7.1 Mail Refused - 68.202.7 - See http://security.rr.com/mail_blocks.htm#security - 20031206)

----- Transcript of session follows -----
... while talking to flmx-2.tampabay.rr.com.:
>>> MAIL From:<root@server.mydomain.com>
<<< 550 5.7.1 Mail Refused - 68.202.7 - See http://security.rr.com/mail_blocks.htm#security - 20031206
554 5.0.0 Service unavailable

--i2AENNDk002134.1078928603/server.mydomain.com
Content-Type: message/delivery-status

Reporting-MTA: dns; server.mydomain.com
Received-From-MTA: DNS; localhost.localdomain
Arrival-Date: Wed, 10 Mar 2004 09:23:23 -0500
Final-Recipient: RFC822; edited@emailaddress.com
Action: failed
Status: 5.7.1
Diagnostic-Code: SMTP; 550 5.7.1 Mail Refused - 68.202.7 - See http://security.rr.com/mail_blocks.htm#security - 20031206
Last-Attempt-Date: Wed, 10 Mar 2004 09:23:23 -0500

--i2AENNDk002134.1078928603/server.mydomain.com
Content-Type: message/rfc822


What's going on? I think it has something to do with the fact that my ISP thinks these emails are spam, which they are not. Is it because it's resolving the dns to "localhost:localdomain"? If so, how do I get rid of that? Remember, I changed my etc/hosts file to reflect server.mydomain.com. Please help.

Hi,

By looking at the error message, it seems that your ISP may have blocked the address 'localhost.localdomain'. However...

1. If you do not have a registered domain name with you or If you are not in a LAN with more than 1 computers, then the following entry in my opinion isnt required. I am assuming that you are trying to send mail from your standalone computer to your ISP e-mail account. If thats correct, then try removing the following line from your /etc/hosts and then send mail again.

192.168.1.xxx server.mydomain.com server

2. You can also see whats actually going on in detail with sendmail by using the -v option

mail -v <your-email-address>

3. Also, just to check, try stopping your firewall

service iptables stop

4. Additionally, monitor /var/log/maillog and check what error messages are being produced other than the ones u just posted.

Regards,

amit

Amit,

Thanks for the reply. I have a strong suspicion that it has something to do with the localhost.localdomain.

I am running the linux box behind my 4 port linksys router, so that NAT IP is necessary in the etc/hosts file. I have 3 other computers running on my home network.

Is there any way to stop the ISP from resolving my linux box as localhost.localdomain? I tried configuring those spoofing setting in the sendmail.conf, and my etc/hosts (and prompt) are configured to have the machine resolve to server.mydomain.com. Please tell me this is fixable without having to run a DSN server on my box.

Help!

Hi.

Any reasonably secure mail server is going to look for an mx record for any server trying to send it mail. We bounce mail all the time here.

If you do not have an mx record for your server I suspect that you have problems.

Ok, I'll bite..

What is an mx record and how to I get one?

An MX record is what DNS uses for a Mail Exchanger for a particular domain.
You can easily run a security check on your ISP mail system by masquerading your sendmail MTA with a domain name that can be resolved. If the ISP resolves the domain and lets you send mail now, then they dont check for valid hosts at that domain. If it is bounced again, then they most likely have host checking and you will have to contact them about adding an MX Record for a domain name that you register.