Sendmail configuration issue

JohnRock · 06-09-2009, 03:45 AM

I have a domain hosted by a 3rd party DNS provider. My mx records for my domain point to their mail servers and I have my email accounts handled by them. I want my Centos production tomcat server to send outgoing mail through sendmail but not receive any incoming mail.

I just changed my A record to point my domain to my production server, and changed my production server hostname to my domain name:
e.g.
hostname=www.mydomain.com

My problem now is this: My server is running sendmail, and when it sends mail to joe@mydomain.com it is now looking for a user named joe on my server and fails if it doesn't find one. If I create a user named joe it will deliver the email into /var/spool/mail/joe.

What I want to happen is for my server's sendmail process to use the mx records located on my 3rd party DNS servers and send the mail to their mail servers so that my server does not have to handle incoming mail.

This was working fine before I changed my server's hostname to the same name as my web domain. That is to say if I send email to joe@mydomain from any other computer it is handled by my DNS server's mail server and my server was behaving that way as well before I gave it the same hostname.

Is there a way that sendmail can send the email to the mail server associated with my domain's mx records even if the email's address is the same as my server's hostname?

I am obviously new to configuring sendmail, and I fear I am missing some important point. I would appreciate any help one can give to clarify this for me.

Thanks!

bathory · 06-09-2009, 07:31 AM

Sendmail by default uses the MX record when it has to deliver email, unless you domain name is listed in /etc/mail/local-host-names. So check that file, remove the line if it exists and restart sendmail.
If your domain name is not listed in local-host-names then I guess you have to configure your mail delivery using virtusertable. Edit /etc/mail/virtusertable and add the following entry:

Code:

@mydimain.com %1@mx-server.mydomain.com

You have to replace mx-server.mydomain.com with the FQDN of your domain's mx server. After editing virtusertable you have to run

Code:

makemap hash /etc/mail/virtusertable.db < /etc/mail/virtusertable

for the changes to take effect.

JohnRock · 06-09-2009, 05:13 PM

Thank you for this great direction. I still have one problem:

I modified virtusertable like this:
@mydomain.com %1@smtp.secureserver.net

But now I get this error:
Jun 9 17:11:38 www sendmail[7493]: n59KeSW7007432: to=<joe@mydomain.com>, delay=00:31:10, xdelay=00:00:00, mailer=esmtp, pri=210576, relay=smtp.secureserver.net., dsn=4.0.0, stat=Deferred: Name server: smtp.secureserver.net.: host name lookup failure

I am not sure if that has anything to do with the fact that I just changed the A DNS record to point to my machine only yesterday...I did not change the mx records so I didn't think there would be a problem..

Or might it have to do with this:
sendmail -d60.5 -bv joe@mydomain.com
translates to:
deliverable: mailer esmtp, host smtp.secureserver.net., user joe@smtp.secureserver.net

Wouldn't the user would have to be something like joe@mydomain.com@smtp.secureserver.net?

bathory · 06-09-2009, 05:31 PM

Are you sure that smtp.secureserver.net can be resolved from your end?
How is your domain's zone file in dns? It should be something like that:

Code:

...
IN MX 10 smtp.secureserver.net.
mydomain.com. A 1.2.3.4
www.mydomain.com. A 1.2.3.4

JohnRock · 06-09-2009, 06:20 PM

Well not exactly sure what you want me to check...The interface I have to manage my MX records on my DNS provider just shows:
0 @ smtp.secureserver.net
10 @ mailstore1.secureserver.net

But I can send outgoing mail through the joe@mydomcain account via smtp.secureserver.net from my home computer (using outlook) fine. It is only on my prod sserver that this is an issue.

But again I wonder could this perhaps simply be because I changed my DNS A record yesterday and the propogation is in flux? Maybe in two more days it will be fine?

Does the mx record require the A record to be fully propagated to resolve correctly?

bathory · 06-10-2009, 12:28 AM

Since you didn't change the mx record of your domain, it has nothing to do with changing the A record of it. Besides the mx server is in a different domain that you have nothing to do with.

What i cannot understand is, that your server's dns is done by secureserver.net, but it cannot resolve smtp.secureserver.net!!!
The fact that you can send mail from home but not from server happens, because you server thinks that mail to @mydomain.com is local, since you've changed its name. Btw what's in /etc/hosts and what is the output of:

Code:

hostname
host mydomain.com
host www.mydomain.com

JohnRock · 06-10-2009, 01:12 PM

Thanks so much for your help. Before posting any further I am going to investigate further with my Hosting provider and try to make sure my DNS and reverse DNS and network settings are configured properly. It is very hard to find thorough documentation on this.