Smtp error 451 Temporary local - please try later on Cpanel Server - smtp

Question

I have a Cpanel Server.
It send emails correctly expect from 1 domain which hosted on the server , so when I try to send email from that domain using roundcube or Horde I got the errror
SMTP Error (451): Failed to add recipient "recipient#exmple.com" (Temporary local problem - please try later).
does anyone know why and how to fix this?
I found the porblem:
After reviewing the file /var/log/exim_mainlog using
tail -f /var/log/exim_mainlog
I noticed that the error was:
2013-05-29 20:04:28 SMTP connection from [127.0.0.1]:36797 (TCP/IP connection count = 1)
2013-05-29 20:04:28 lowest numbered MX record points to local host: domain.com (while verifying <user#domain.com> from host localhost.localdomain (domain.com) [127.0.0.1]:36797)
2013-05-29 20:04:28 H=localhost.localdomain (domain.com) [127.0.0.1]:36797 sender verify defer for <user#domain.com>: lowest numbered MX record points to local host
2013-05-29 20:04:28 H=localhost.localdomain (domain.com) [127.0.0.1]:36797 F=<user#domain.com> A=dovecot_login:narena temporarily rejected RCPT <recipient#exmple.com>: Could not complete sender verify
2013-05-29 20:04:28 SMTP connection from localhost.localdomain (domain.com) [127.0.0.1]:36797 closed by QUIT
so the main problem was:
lowest numbered MX record points to local host
after couple of search I found the soluation in http://forums.cpanel.net/f5/lowest-numbered-mx-record-points-local-host-73563.html
which was to:
login to WHM and go to Main >> DNS Functions >> Edit MX Entry for the domain
set MX priority to 0 for the related domain and save.

Answer 1

I had the same problem after running a script to fix directory permissions on a cPanel-powered server (CentOS 6.5). I checked the logfile (tail -f /var/log/exim_mainlog) and found this error:
require_files: error for /home/user_name/etc/domain.com: Permission denied
Just ran the following command and the issue was fixed:
chown -R user_name:mail /home/user_name/etc/
Hope this helps someone.

Answer 2

check the the file /var/log/exim_mainlog to see more information about the error
tail -f /var/log/exim_mainlog
while trying to send email

Answer 3

Check your MX Entry in Cpanel, if the existing domain priority is less than or equals to 0, set it to 1. Mine is fixed. Hope it will help you.

Answer 4

Wow, after about an hour of searching and meddling with different files, I'd caution any novice not to venture out editing anything before you have a backup or image if your server, as you can cause irrevocable damage to your server. So many people talking garbage about what you should do or test without any real solution.
Anyways, here's what worked for me:
Real problem: Exim was updated to latest version which has loads of bugs like this issue.
How I fixed my server:
Authenticate to Linux via SSH and run the command lines through which we download and install the old version of EXIM.
Command Line 1: wget https://ca1.dynanode.net/exim-4.93-3.el7.x86_64.rpm
Command Line 2: rpm -Uvh --oldpackage exim-4.93-3.el7.x86_64.rpm
Command Line 3: systemctl restart exim
Command Line 4: Systemctl restart clamd
Command Line 5: systemctl restart spamassassin
Optional: just type "Reboot" to restart your server
The command lines above does the following:
Downloads the old package (I'm sure you can google other sources with this file)
Install the old package without prompt
Restart the Exim service
Restart the Clamd Service (AV)
Restart the spamassassin service (Spam Filter)
Restart outlook or whatever you use for mail client and send an email. Mine works, hope yours do too.