Simple sendmail configuration on Redhat 6.5

SuperSic · 04-22-2015, 02:13 AM

Hi All, having a bit of a nightmare getting sendmail to work on a redhat 6.5 client. Basically I want it to forward on all external emails to a smart relay, so I've updated the DS line to point to my smart relay and restarted sendmail. This has worked for many years on multiple different OS's but not on this one at this time.

I've disabled postfix, removed postfix, removed sendmail, re-added sendmail, re-configured sendmail, verified DNS, ran a "telnet smartrelay 25" and can get connectivity, but whenever I try sending an external mail it trys to route it internally and then I get a return email saying it can't resolve the external email addresses.

Has something fundamental and basic changed because this configuration works on multiple other clients I support.

Here is the returned mail:

Message 2:
From MAILER-DAEMON@hostname.blah.blah Tue Apr 21 17:07:58 2015
Return-Path: <MAILER-DAEMON@hostname.blah.blah>
Date: Tue, 21 Apr 2015 17:07:58 +0100
From: Mail Delivery Subsystem <MAILER-DAEMON@hostname.blah.blah>
To: root@hostname.blah.blah
Content-Type: multipart/report; report-type=delivery-status;
boundary="t3LG5R9o017225.1429632478/hostname.blah.blah"
Subject: Returned mail: see transcript for details
Auto-Submitted: auto-generated (failure)
Status: RO

Part 1:

The original message was received at Tue, 21 Apr 2015 17:05:27 +0100
from root@localhost

----- The following addresses had permanent fatal errors -----
-c
(reason: 550 5.1.1 <-c@hostname.blah.blah>... User unknown)
(expanded from: -c)
-f
(reason: 550 5.1.1 <-f@hostname.blah.blah>... User unknown)
(expanded from: -f)

----- Transcript of session follows -----
451 remotehost.com: Name server timeout
451 anotherremote.com: Name server timeout
... while talking to [127.0.0.1]:
>>> DATA
<<< 550 5.1.1 <-f@hostname.blah.blah>... User unknown
550 5.1.1 -f... User unknown
<<< 550 5.1.1 <-c@hostname.blah.blah>... User unknown
550 5.1.1 -c... User unknown
451 remotehost.com: Name server timeout
451 anotherremote.com: Name server timeout

Part 2:
Content-Type: message/delivery-status

Part 3:
Content-Type: message/rfc822

From root Tue Apr 21 17:05:27 2015
Return-Path: <root>
From: root <root>
Date: Tue, 21 Apr 2015 17:05:27 +0100

Any suggestions gratefully received as I'm beginning to loose the will to live with this one...

Thanks Sic

TB0ne · 04-23-2015, 08:15 AM

Quote:

Originally Posted by SuperSic

Hi All, having a bit of a nightmare getting sendmail to work on a redhat 6.5 client. Basically I want it to forward on all external emails to a smart relay, so I've updated the DS line to point to my smart relay and restarted sendmail. This has worked for many years on multiple different OS's but not on this one at this time.

I've disabled postfix, removed postfix, removed sendmail, re-added sendmail, re-configured sendmail, verified DNS, ran a "telnet smartrelay 25" and can get connectivity, but whenever I try sending an external mail it trys to route it internally and then I get a return email saying it can't resolve the external email addresses.

Has something fundamental and basic changed because this configuration works on multiple other clients I support. Any suggestions gratefully received as I'm beginning to loose the will to live with this one...

Sendmail has that effect on people.

It sounds as if you want to use/enable the mailertable feature:
https://www.sendmail.com/sm/open_sou...lertables.html

...which will let you select the host mail goes to, depending on the domain. This has an explanation a bit simpler to follow:
http://www.cyberciti.biz/faq/force-s...or-mailserver/