?
Solved

sendmail refuses to use smart host

Posted on 2010-08-27
3
Medium Priority
?
594 Views
Last Modified: 2013-12-18
I have a problem with the way sendmail sends messages.  By default, it uses user@host.domain.com which fails with some on the outside because of the dns lookup.

I was able to get the masquerade working so it sends as user@domain.com but fails for local users.  If a local user on domain.com was the recipient, sendmail tries to deliver locally, fails because of no local account, and generates an NDR.

I decided to use exchange for smart host.  In my test environment, I added the lines in sendmail.cf to use smarthost.  I used m4 to create then restarted sendmail.  I tested to my hotmail account and was successful.  Then I tested to my domain.com account and was delivered.  In the message headers it showed that Exchange received it from the linux box.

Here is where the problem comes in.  When I do this on my production box, the masquerade works, but will NOT use smart host.  It keeps trying to deliver locally and fails with NDR.  I have done a couple times, even copying the sendmail.cf from the test machine.  Yet after using m4 to regenerate and restarting sendmail it refuses to use smart host and is treating like a local account, refusing delivery for domain.com recipients.

Both systems are CentOS 5.5 with the same sendmail packages, on the same network, on the same switch with no firewall between each other or Exchange.  Both resolve DNS properly when I do host -t mx domain.com so I can't make sense as to why the same sendmail configuration works on one system and not the other.
0
Comment
Question by:Seth Simmons
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 35

Author Comment

by:Seth Simmons
ID: 33546014
I just took another production server configured the same way as the other (package profile, etc).

I made the same masquerade and smart host changes for sendmail and it's working fine.
No idea why the other production server refuses to use smart host.
0
 
LVL 29

Accepted Solution

by:
Jan Springer earned 2000 total points
ID: 33546096
Do you have 'domain.com' in /etc/mail/local-host-names?
0
 
LVL 35

Author Comment

by:Seth Simmons
ID: 33546284
OMG...you just saved my sanity!

That was it.  I commented it out and it's using smart host.
0

Featured Post

Get 15 Days FREE Full-Featured Trial

Benefit from a mission critical IT monitoring with Monitis Premium or get it FREE for your entry level monitoring needs.
-Over 200,000 users
-More than 300,000 websites monitored
-Used in 197 countries
-Recommended by 98% of users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Resolve Outlook connectivity issues after moving mailbox to new Exchange 2016 server
Phishing attempts can come in all forms, shapes and sizes. No matter how familiar you think you are with them, always remember to take extra precaution when opening an email with attachments or links.
In this video we show how to create a Resource Mailbox in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: Navigate to the Recipients >> Resources tab.: "Recipients" is our default selection …
In this Micro Video tutorial you will learn the basics about Database Availability Groups and How to configure one using a live Exchange Server Environment. The video tutorial explains the basics of the Exchange server Database Availability grou…
Suggested Courses
Course of the Month14 days, 12 hours left to enroll

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question