5.4.4 (unable to route: no mail hosts for domain)

beserious · 04-03-2014, 03:57 AM

Hello,

I am getting this error on all the emails...

5.4.4 (unable to route: no mail hosts for domain)...I have installed cpanel on the server and all dns records seems right but dont know why this happens...

I am using solusvm and all vps are using openvz visualization... All the servers have the same issue and get 5.4.4 (unable to route: no mail hosts for domain) in the log...

is this issue from my side or from the Data center?

Please help me to resolve this issue..

Thanks

Ser Olmy · 04-03-2014, 07:35 AM

"No mail hosts for domain" indicates that the server generating the error message was unable to locate an MX record for the domain in question. This could be a DNS problem (local or on the Internet), or it could be an issue with the server configuration.

Try running this command on the server and post the results:

Code:

nslookup -q=MX <domainname.com>

Replace <dommainname.com> with the domain of the e-mail recipient.

beserious · 04-03-2014, 07:37 AM

root@server [~]# nslookup -q=MX mithyache.com
Server: 8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
mithyache.com mail exchanger = 0 mithyache.com.

Authoritative answers can be found from:

Ser Olmy · 04-03-2014, 09:08 AM

I've never seen "0" as a priority value before (is it even valid?) but other than that the response looks good.

Can you reach port 25 on the mail exchanger from the server (telnet mithyache.com 25)? Because I certainly can't.

beserious · 04-03-2014, 09:22 AM

No I can not telnet...i get timeout...

Ser Olmy · 04-03-2014, 04:09 PM

Well, there's your problem. If you can't reach TCP port 25 of the mail server, you can't deliver mail.

Since it takes a while for the connection attempt to time out, I'm guessing it's a firewall issue.

beserious · 04-04-2014, 12:24 AM

I have already off the firewall.... but same issue coming.... 1 thing is I am not able to ping to my gateway from the ssh..... I am able to ping gateway from my local machine.... could that be the issue?

Ser Olmy · 04-04-2014, 09:52 AM

The problem is this: TCP port 25 on the mail server for the mithyache.com domain cannot be reached from the Internet. That's what's causing the error message, and that's what needs to be fixed.

If you're the person managing this server, you will have to figure out why traffic is not getting through. If you're not responsible for managing the server, you'll have to report the problem to the system administrator in question.

Whether a ping packet being blocked is related to this issue or not, is impossible to say without a lot more information. Ping uses an entirely different protocol, so there's no obvious connection.

Edit: Corrected typo: the port number should be 25, not 22

beserious · 04-04-2014, 09:57 AM

Hi,

I am able to login to ssh via port 22...could u tell me what should I check on the server?

Ser Olmy · 04-04-2014, 10:12 AM

Quote:

Originally Posted by beserious

I am able to login to ssh via port 22...could u tell me what should I check on the server?

The port number in my previous port was wrong. SMTP user TCP port 25, not port 22. Sorry about that.

You should check the firewall settings (iptables-save -t filter will dump the ruleset).

Does the server have a public IP address assigned to a network interface, or does internet access go through a router performing NAT?

beserious · 04-04-2014, 10:18 AM

I played with firewall.

I completely stopped the firewall and also tried by flushing all rules...my all ips are dedicated...i am using server for emailing only..

Ser Olmy · 04-04-2014, 11:46 AM

Then why didn't you post the output from iptables-save -t filter as I suggested? Let's see the output from netstat -plt as well.

(Of course, if you prefer "playing" with the firewall rather than getting help that's just fine by me, but in that case I wonder why you posted a question to this forum in the first place.)