Can't receive incoming email from external addresses on Exchange 2003

kj_syence used Ask the Experts™
Hey folks,

I'm having issues with our exchange server where we can send emails internally and externally and receive emails internally, but we are not able to receive any emails from external sources. The external sources doesn't seem to be getting any type of bounce back either. I did some searches using message tracking and there is no trace of these emails hitting our server.

What's the first thing that I should look at. Is it safe to rule out DNS if I can send emails out?
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My MX records seem to be setup properly as well. Kind of doesn't make sense. This just started happening out the blue a couple days ago.
Try to use
Firstly do a mx lookup for your domain and then SMTP test.

Look also at SMTP logs at your server


I run the mx lookup tool and it doesn't find anything.

When I start the smtp diagnostics I get "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond"

I took a look at our smtp logs at C:\WINDOWS\System32\LogFiles\SMTPSVC1...

What exactly should I be looking for?
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if you cannot find your MX record using mxtoolbox, then something has happened to your DNS records
you will need to check you external DNS record with whoever is the current namespace authority
If you enter in mx lookup let say domain  (do not use or format!) you should get this kind of record:               mx    
Pref      Hostname      IP Address      TTL            
10      30 min      SMTP Test      Blacklist Check

Then if you click at SMTP test you should get something like this:

Monitor This smtp ESMTP ESMTP Postfix

 OK - resolves to
 OK - Reverse DNS matches SMTP Banner
 0 seconds - Good on Connection time
 Not an open relay.
 6.427 seconds - Warning on Transaction time

Session Transcript:HELO
250 [16 ms]
250 2.1.0 Ok [16 ms]
550 5.7.1 <>: Recipient address rejected: does not accept e-mail [94 ms]
221 2.0.0 Bye [16 ms]

Do the same for your domain.


I added our domain as you desribed davorin, for mxlookups, but nothing.

I run a nslookup against it and I see both our DC's show up with correct IP's. I then turn around and run a DNS lookup by clicking on one of our DC's, and the test states "no records found"

this was all done on

Both our DNS servers are external and contain our MX records, listing the name of our Exchange.

I also just received a kick back from an external email address that was used to test and it states that it has communicating with the DNS server. Only problem is, I'm not sure which DNS server is causing this issue. Is there a way to see where communication is having a hang up?


*has communication issues.

Sorry, typing fast.

the specefic error I get from google when trying to email one of our email addresses is "DNS Error: Timeout while contacting DNS servers"

try to check DNS records for your domain using
Select ANY type of records and look if MX record and appropriate A record is set correctly
IP address of server listed under domain box leave as it is.

"no records found" is normal for

You can have here:
- external access problem to your DNS server (you will get no results from
- problem with DNS records at your server (results form centralops will be incorrect)
- external to internal SMTP traffic is not working correctly

Please let me know if centralops results are correct.
"kick back from an external email" - sorry, I don't get what you mean with that.

Have you done any changes to your system (DNS, internet access, mail server) prior the problem arises?

i would start this troubleshooting with using Nslookup.
1. Start a command prompt
2. type "nslookup" hit enter
3. type "set type=mx" in the nslookup box, hit enter
4. typ "yourdomain.topdomain" ( or whatever your domain is, the ip address is for one of the dns servers so you can see how it looks on the internet), hit enter.
5. your result should look something like this.
Server:  []

Non-authoritative answer:  MX preference = 10, mail exchanger =

If your DNS is setup properly,then you should go on testing your SMTP connector byt using telnet
1. Open a command prompt
2. type telnet smtp
3. helo
4. mail
5. rcpt
6. data
7. test
8. .
9. <enter>

If you cannot telnet on port 25/SMTP from internet, then you have issues either with your firewall or with your SMTP connector.

Try this and get back for more help.



I receive no results. It states that it times out. What I meant by "kick back" was a NDR.

We did not make any changes to DNS, internet access, and our mail server. (As far as the equipment that I own)

What is the domainname? I can have a look from here.



.mil is not a valid top domain name as far as I know.

So if your E-mail is then it will not work. Due to .mil is not a valid ICANN aproved topdomain



I believe it should. What type of lookup were you attempting to do?
Hi yes you are right. .mil is a US only top domain name. Tough I cannot reach any authorative dns server to lookup any domain names from my Swedish computer.


; <<>> DiG 9.7.3 <<>>
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47310
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 6
;; WARNING: recursion requested but not available

;                  IN      A

mil.                  172800      IN      NS
mil.                  172800      IN      NS
mil.                  172800      IN      NS
mil.                  172800      IN      NS
mil.                  172800      IN      NS
mil.                  172800      IN      NS

;; ADDITIONAL SECTION:            172800      IN      A            172800      IN      A            172800      IN      A            172800      IN      A            172800      IN      A            172800      IN      A


; <<>> DiG 9.7.3 <<>>
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

I get the same answer from all the authorative servers. I guess it's the reason for the other MX checkers wont work either.

So if I would try to send an e-mail to my mailserver will never find your SMTP server by DNS name.

NDR does not need DNS resolution. It is generated in direct SMTP server to server communication.

Also I can not get any records from your domain. As it is US Military domain, it could be restricted in some parts of the world.
Maybe you should contact the registrar for your domain. I doubt that the problem is at your place.


I called my registrar. Waiting on a callback right now. Hopefully I receive some insight on what the heck happened.


Turns out the domain we share the backbone with had fiddled with our MX records over the weekend. Issue resolved. Points going out.
Glad you have solved the problem and thx for points.

I have checked again your domain at and I get another error.
It says that RDNS test failed. Maybe it is the problem because you are using capital letter in SMTP banner. Some linux mail servers are sensitive on this and you could have problems sending mails to these servers.


Thanks for the followup davorin. I will look into tomorrow. What type of RDNS test you did on mxtoolbox? I can't seem to find the same test.


Nevermind, I see it now. It's part of the smtp test.

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