Web Hosting Talk : Web Hosting Main Forums : Hosting Security and Technology : unrouteable mail domain

[the_pm]

Ok, I've had this ongoing problem sending and receiving email with an exchange server, and I can't for the life of me figure out why.

Here's the issue. Every time I attempt to connect from our server, I get an "unrouteable mail domain" error.

When this first started happening, I checked their MX records and found they had configured them improperly. So, I gave them this info, and a month or two later, they have it right. I go to email them again, and I'm getting the same error!

What could possibly be causing the problem? They can't send to our server. We can't send to theirs. Our MX records are fine. Theirs are fine now as well. Typically, if I'm not mistaken, the unrouteable mail domain error means either you've spelled the domain name wrong (which is NOT the case), or the error is on the receiving end. So, what could that error be, if not the MX records?

Thanks!

[glued2]

Is your server doing call backs or something that could be preventing their mail getting to you?
Can they send email to anyone externally?
So you are 100% sure the dns is now correct and the domain is valid? Not a local dns entry on your mail server that's overwriting the global setting?

[the_pm]

Is your server doing call backs or something that could be preventing their mail getting to you?

Nothing of which I am aware. I'm not the only one who's had ongoing issues sending and receiving from the destination server, FYI.

Can they send email to anyone externally?

They can, but I guess I gave the rest of the answer to this question above. They've been having issues sending and receiving with other servers as well. Plus, the problem was immediate, from the moment we brought our server online, this has been an issue.

So you are 100% sure the dns is now correct and the domain is valid?

On my end? Yes, our DNS is set up properly. I can't tell you what is or isn't set up properly on their end. Their MX records were not, but that has been rectified. Would a local DNS entry on our server overwrite a setting when sending mail? Would this happen across multiple virtual accounts? I've tried sending from an account on the the primary server IP as well as on one of the additional IPs. Everything is sending from the primary, as expected.

[peteysa]

What happens when you try to send email directly to their mail server?

telnet mailserver.someplace.com 25

If you dont get a response with the telnet then its going to be something with IP communication between the 2 locations.

I once ran into a situation where 2 customers were using the same provider for their T-1 and one of them had their subnet mask incorrect on their firewall or router which prevented them from emailing each other.

Good Luck!

Dan

[ComputerX]

I can't help you much with Exchange specific issues. Sorry. It has been a couple years since I managed Exchange servers.

For the mail the first thing to do is to try a SMTP session *from your mail server* to theirs. Instructions at http://www.pantz.org/email/misc/smtptelnet.shtml

Have them do the same. Be sure to do it from your server. It is easy to be lazy and do it from your work machine but sometime that confuses the issue.

You can query their public DNS servers. Use whois to find what their authoritative server is and then either dig@ns.them.dom or use nslookup and specify their server. I find it easier to use nslookup in interactive mode on a Windows box.

If you don't have a whois client you might be able to use a web based one.

http://www.betterwhois.com/bwhois.cg...=equentity.com gives

   Registrar: WILD WEST DOMAINS, INC.
   Whois Server: whois.wildwestdomains.com
   Referral URL: http://www.wildwestdomains.com
   Name Server: NS1.EQUENTITYHOST.COM
   Name Server: NS2.EQUENTITYHOST.COM
   Status: REGISTRAR-LOCK
   Updated Date: 09-dec-2005
   Creation Date: 07-apr-2005
   Expiration Date: 07-apr-2006

So I would do something like this on a Windows box.

C:\>nslookup
Default Server:  ns.me.dom
Address:  10.1.1.51

> server NS1.EQUENTITYHOST.COM
Default Server:  NS1.EQUENTITYHOST.COM
Address:  64.38.7.202

> set q=mx
> equentity.com
Server:  NS1.EQUENTITYHOST.COM
Address:  64.38.7.202

DNS request timed out.
    timeout was 2 seconds.
equentity.com   MX preference = 0, mail exchanger = equentity.com
equentity.com   nameserver = ns1.equentityhost.com
equentity.com   nameserver = ns2.equentityhost.com
equentity.com   internet address = 64.38.7.202
ns1.equentityhost.com   internet address = 64.38.7.202
ns2.equentityhost.com   internet address = 64.38.7.203
>

Have them do the same and you should have a good idea what the issue is. Unless it is an Exchange routing problem. It has been too long since I had to muck with that.

Good luck,

Dan

P.S. A MX pref of 0 doesn't give you anyplace to go if you have to sneak another server in under it for a bit. I'd change that.

[the_pm]

Thank you very much Dan and Dan for your responses. I went into shell and sent them a message through command line. It didn't get immediately returned to me like is does through Exim, though the final statement was that the message was going into queue. I checked the server mail queue, and it wasn't there. So I assume it was delivered. I also checked the error log, and no error was generated by my sending that message.

I guess I need to wait and see if I get a response. They're not in right now, so I won't know until tomorrow. I'll call them and ask.

Thanks again! This is very educational I'm not the server admin, and I don't want to bug our admin for something I can handle on my own...if I can handle it on my own.

[NyteOwl]

I had a similar problem at one of my hosts bouncing mail forwarder through a mail address on my domain and it was a problem with one of the secondary scripts in use by Exim. They fixed it but off hand I don't know which script was the problem. I'll ask tomorrow if I remember and let you know.

[the_pm]

Ok, I just got word that the telnet email exchange worked, and they were able to email me from their account. I'm going to try sending through Exim again and we'll see what happens.

[the_pm]

Ok, everything seems to be working now!

For my tests, I sent a message via telnet, I sent one through a peripheral account on our server via Horde, and then I sent one from the actual account that was causing problems in the first place. It worked. Everything worked!

If the destination server just recently set up their MX records properly, would there be lag time between set up and the ability to use the new settings? Is there propagation time on MX records? Is it possible this might be why we saw the right settings but still couldn't exchange mail yesterday?