RedHat Mailx

inyourmind · 11-06-2014, 02:11 PM

Hello,
i am using mailx command like below:
mailx -r 'boss@comp.com' -s 'Email Send' 'user@comp2.com' < file_body

And the email successfully sent.
I don't understand how it get the SMTP Server.
My user don't have the ~/mailrc

I have the standard configuration of /etc/postfix

Inside /var/log/maillog i have the name of the SMTP Server but it change sometimes.

Maybe mailx get the SMTP Server by a dns from /etc/resolv.conf??

Has to do something the route in /etc/sysconfig/network-scripts?

bathory · 11-08-2014, 02:17 AM

Quote:

And the email successfully sent.
I don't understand how it get the SMTP Server.
My user don't have the ~/mailrc

From mailx manpage:

Code:

smtp      Normally, mailx invokes sendmail(8) directly to transfer messages.  If the smtp variable is set,
              a SMTP connection to the server specified by the value of this variable is used instead.  If the
              SMTP server does not use the standard port, a value of server:port can be given, with port as  a
              name or as a number.

So mailx uses the sendmail binary (postfix has one too) to submit the message. Message is then sent by the MTA (postfix in your case). It's the MTA that uses dns to find the MX server of the recipient in order to deliver the message.

Quote:

Maybe mailx get the SMTP Server by a dns from /etc/resolv.conf??

No. As mentioned above, it's the MTA that uses dns to find the MX server of the recipient domain

Quote:

Has to do something the route in /etc/sysconfig/network-scripts?

Nope

inyourmind · 11-09-2014, 10:57 AM

Ok i get it.
If i had a right configuration of DNS but postfix don't reach any MX Server, is it possible that i have to configure a route?

bathory · 11-09-2014, 12:08 PM

Quote:

Originally Posted by inyourmind

Ok i get it.
If i had a right configuration of DNS but postfix don't reach any MX Server, is it possible that i have to configure a route?

If you have a right dns configured, then your box (and postfix of course) should be able to find the MX record of the recipient domains.
Most likely you need to use your ISP mailserver as a relayhost, because usually ISPs block port 25 traffic. If that's the case, use:

Code:

relayhost = mail.my-isp.com

If you need authentication to connect to your ISP mailserver, have a look here

Regards