SMTP LOG shows incoming and outgoing email to "some" domains as the incorrect domain name

Most of our mail from the internet gets through to us.
However, some internet users are unable to send email to us.
As I look at the smtp log the domain name that shows incoming
mail is wrong.
I have tried to clear our DNS cache, purge old entries and refresh the DNS database on on our Windows 2000 server running DNS and Exchange 2000.
For example if I send email to a company called (not the real name,) it should go to   The smtp log shows the mail is trying to go to
Incoming email from should show up in our smtp log at, it also shows email coming in as
This is happening to about a dozen companies sending us email from the internet from different domains. This is a small percentage of our business, everything else gets through fine.
I called our internet service provider, they say there is nothing wrong with their DNS entries.
It is unclear if we need to be resolving an Exchange problem or a DNS problem. IF it is a DNS issue we do not see where this is coming from.
I did a trace route for the domain name and it resolves to the correct ip address.
However, the smtp log for Exchange 2000 is trying to route the mail to a domain called
This is wrong, and this name does not resolve to any ip address.
How do I correct this??
Help! We are loosing business because of this!!!
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LimeSMJConnect With a Mentor Commented:
Try looking up their MX record in and see if is set correctly in there...  

If in fact it is supposed to be, that may be a secondary MX record or that sender has their RDNS setup wrong...
Are you using a SPAM filter or some kind of software that does reverse DNS checking?
mharmon777Author Commented:
We use Symantec antivirus for Exchange, that is all.
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mharmon777Author Commented:
I have unloaded the Symantec antivirus for Exchange, have changed my dns entries in network settings, changed my forwarder information to another dns server in my dns service.
I have even shutdown my dns service and my Symantec antivirus service, the email still trys to go to the wrong dns name.
Incoming shows email coming from the wrong domain name??
mharmon777Author Commented:
This poses another question. They can send to other companies just fine? Why us?
Should I create some kind of DNS entry in our Windows 2000 environment that resolves the to the actual ip address of
I gave a example domain name for the sake of discussion. The actual domain name is
My smtp gateway keeps trying to send responses to, and incoming email logs in my
smtp gateway as and does not get in.
Out going email gets to them just fine, incoming to us does not. IT used too.....
They send to all kinds of other companies just fine, it is just sending to us????
As I said, there are about 6 companies we know of that email just does not get in.

mharmon777Author Commented:
How do I change the FQDN entry for the SMTP gateway for these domains? Perhaps this is the problem and needs to be changed?
mharmon777Author Commented:
I contacted Microsoft, they gave me instructions on how to send an email via ftp commands.
I had the problem company email me a message using ftp commands.
The email go through.
So.......... either something is messed up on the dns on the customer sending us the mail or the ISP has issues concerning routing mail to us from this company.
We bypassed all dns by using ftp and that worked.
What do you think?
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