Bizarre email issue

Voltage · 27 Mar 2009 at 11:57

Hi,

My company is having a problem emailing a client, everytime we email them we get an error message

<domainnamehere> domain does not resolve

also, we can not ping that domain from our network, we are emailing other clients fine and the client says they are recieving email fine from everyone else.

any ideas what could be causing this and how to fix it?

We unfortunately are using Kerio Mail Server

Sin_Chase · 27 Mar 2009 at 11:58

What is the domain?

Use - http://centralops.net/co/EmailDossier.aspx

Check it and see what comes back, it might well be them, not you.

Voltage · 27 Mar 2009 at 12:06

im thinking it is us because we can send them email from things like hotmail and i can ping their domain from home.

just ran the test on the address using that link you put there and it passed.

Sin_Chase · 27 Mar 2009 at 12:06

What is your environment?

Eg - What serves as your DNS?

Get the known IP from one of your other resolutions and from your site go back to basics

telnet 111.222.333.444 25

What do you get back.

Voltage · 27 Mar 2009 at 12:20

i get a connect failed when i try to telnet to it.

but that could be the firewall not allowing that. our mailserver is hosted outside our firewall, and nope im not giving out our ip address

Sin_Chase · 27 Mar 2009 at 12:23

Point of telnetting is that you are bypassing your mail server entirely.

Did you telnet to it by the IP?

Voltage · 27 Mar 2009 at 12:25

yes i did

randal · 27 Mar 2009 at 12:34

Do you hand your mail off to an external provider for AV/spam etc..? Like Messagelabs?

On the mail server itself can you telnet out to another known working mail gateway? i.e smtp.googlemail.com?

As mentioned above, can you resolve the mail host you're sending to in DNS? Do an MX lookup on http://www.demon.net/toolkit/internettools/ and try and ping/telnet/lookup the host.

Then look at what DNS server your mail server uses, is it internal or are you using internet DNS like OpenDNS?

Cheers

Voltage · 27 Mar 2009 at 12:54

we dont have message labs

we use microtech for our dns, been on their site and cant find any option that will solve this issue.

everything appears to be resolving fine on that site

randal · 27 Mar 2009 at 13:01

I think you'd need to hop onto your mail server and do the connectivity tests really, that's your next step.

Voltage · 27 Mar 2009 at 13:04

its a bloomin mac box

so glad all of this kit is getting thrown out the business in a few months for brand spanking new £500k infrastructure

randal · 27 Mar 2009 at 13:18

Shouldn't be a problem, same commands - just a different terminal

Sin_Chase · 27 Mar 2009 at 15:05

If he cant resolve the MX records on his client machines then there is a problem with DNS regardless of the Mail Exchanger.

This is assuming his clients can get out onto the internet.

Configure one of your clients DNS manually and point it at an external source, you can use open DNS on either 208.67.222.222 or 208.67.220.220.

Then try resolve.

Run an ipconfig /flushdns first though.

Voltage · 2 Apr 2009 at 16:34

feedback is i still cant get a dns response directly from the mail server.

i changed the dns server of my domain controller to those above and could then ping and nslookup, email issue however still occurs. its really really strange

Sin_Chase · 3 Apr 2009 at 12:22

Can you clarify.

With open DNS on the DC you could resolve the domains MX records and telnet to it on port 25?