A bit of Exchange help

nightmare99 · 12 May 2015 at 08:41

I'm helping a friend out with a small mail problem on an SBS 08 box so exchange 2007, generally everything works fine but domain users seem unable to email anybody @arun.gov.uk
They get message delayed NDRs then finally "550 4.4.7 Queue expired"

I suspect it may be relevant but an nslookup arun.gov.uk from the server does not resolve to anything.

Any ideas?

#Chri5# · 12 May 2015 at 09:10

What DNS does the box have? If it's pointing to itself for AD DNS, what forwarders are set in the DNS Server?

http://www.intodns.com/arun.gov.uk suggests the domain has a valid MX record.

nightmare99 · 12 May 2015 at 09:49

Yeah its pointing to itself for DNS, in the forwarders there is the router's IP, the ISP's primary/secondary IPs & google's IP.

On the IP v6 network interface there is a static address set but the primary DNS is set to loopback

:1), I presume this is ok?

I think I will have to have a dig through the SMTP logs to see what is happening.

Ploppy2k3 · 12 May 2015 at 11:52

look at your DNS server configuration and importantly the forwarders config. usually this will point to you ISP DNS but sometimes its incorrect or out of date.

nightmare99 · 13 May 2015 at 07:28

Ok so it perhaps looks like a DNS problem I am getting this error in the smtp send log
"Domain of sender address [email protected] does not resolve"

Now the domain does actually resolve ok however if I run the find problems tool on mxtoolbox it does report "None of the name servers responded in a timely manner", is it possible the name servers are mis-configured or not working correctly?

Ploppy2k3 · 13 May 2015 at 17:25

in you DNS Manager go to the properties of the server and then forwarders. make sure your ISP DNS servers are in there and add 8.8.8.8 (google DNS) as well to be sure and then test

nightmare99 · 14 May 2015 at 06:52

Yes the isp DNS & google DNS are in the forwarders. Looking at the logs Exchange connects to the recipient mail server and tries to send but the recipient mail server is unable to resolve the sending domain and closes the connection.

PooKer · 14 May 2015 at 09:30

is rdns setup?

ping -a x.x.x.x

with x.x.x.x being the external IP of the box that's sending the mail. If it just pings the IP you know rdns isn't setup.

For example:

C:\Users\Ian>ping -a 87.117.225.115

Pinging bnc.pooker.eu [87.117.225.115] with 32 bytes of data:

Is what a correct rdns will return with.

anything I don't mind · 14 May 2015 at 10:12

Run the best practice analyzer on your domain controller that handles DNS and run the exchange server BPA as well.

Ploppy2k3 · 14 May 2015 at 10:41

nightmare99 said:
Yes the isp DNS & google DNS are in the forwarders. Looking at the logs Exchange connects to the recipient mail server and tries to send but the recipient mail server is unable to resolve the sending domain and closes the connection.

in which case you need to get an RDNS record setup by your ISP to point to the name of your server as suggest 2 posts up

nightmare99 · 14 May 2015 at 10:43

I have checked rdns with mxtoolbox and it passes fine.

If I run a ping -a myexchangeip it gives

Reply from myexchangeip: bytes=32 time=40ms TTL=59

I have run the BPA and it shows no real error or warnings.

I suspect this is the issue below although if I do an nslookup it resolves ok, is it possible the name servers are just not responding quickly enough for the recipients mail server to resolve the DNS of the sending domain?

PooKer · 14 May 2015 at 10:51

Its the line above with the ping tool that we're interested in.
Pinging bnc.pooker.eu [87.117.225.115]

If its got the mail.domain.co.uk or whatever you've called the server or if it goes straight to:
Pinging x.x.x.x with 32 bytes of data:

Are you using the tool:
http://mxtoolbox.com/ReverseLookup.aspx
And putting in the external IP address of the exchange box?
Mine reports this back:

Type IP Address Domain Name TTL
PTR 87.117.225.115 bnc.pooker.eu 3 hrs

nightmare99 · 14 May 2015 at 10:55

PTR tool result

PooKer · 14 May 2015 at 10:58

port-16.xxx.th.newnet.co.uk does not resolve to anything and looks a little generic (more advanced spam filters will block that as its a default ISP rdns)

jameshurrell · 14 May 2015 at 11:08

PooKer said:
port-16.xxx.th.newnet.co.uk does not resolve to anything and looks a little generic (more advanced spam filters will block that as its a default ISP rdns)

Tend to agree. If arun.gov.uk is doing any kind of advanced lookup or grey listing they may reject that rDNS. Can you not ask your ISP to modify the rDNS of your static IP (I presume it's a static IP and not dynamic?) to match the A record you use for your mail server? In SBS land this tends to be set to remote.domain.com or something similar.

nightmare99 · 14 May 2015 at 11:16

Yeah its on a static and a rDNS / PTR was setup by the ISP some time ago, perhaps something has changed then as its not correct now. Can't believe I missed that, will contact the ISP and get them to correct it.

EDIT: How strange the issue seems to have corrected itself now.

Cheers for the help.