Domain of sender address does not exist - NDR #5.1.8 smtp;553 5.1.8 generated

   I hope you can help me.
   I am running Exchange Server 2003 in my organization. The server sits on the Active Directory server and the DNS Server as well. I have configured my company's domain name on it so that the emails will go out as

   I have configured a reverse lookup zone and forward lookup zone correctly for my mail server (with PTR and MX Records) and my mails can go out fine.

  However, when userA send mails to this particular domain, say, the mails bounce back with this error.

< #5.1.8 smtp;553 5.1.8
<>... Domain of sender address does not exist>

  I have gone thru many archives but I can't seem to find the answer! Please help!
  Thank you.

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David WilhoitSenior Consultant, ExchangeCommented:
your domain doesn't seem to be public; what is your public DNS name? If it is public, does the DNS know where to route email for your domain name?


If you need to send mail externally, the domain you use for your e-mail addresses (SMTP that is) need to be recognized within the DNS naming convention. So the .my needs to go, it should be Only thing is that you need to be the owner of this domain, else, you would need to deposit a new domain name with your ISP and make sure your e-mail addresses get this DNS name ( Then, make sure to change the RUS to instead of and you should be goo to go (also do a forced update on the RUS and make sure to delete the old e-mail addresses).
waimingAuthor Commented:
Hi Kidego,
   My domain's public DNS name is
   If it is not public, is there a way to make it public? How do I go about that?
   The .my is required because I am from Malaysia and the domain name is registered with MYNIC (Check - WHOIS section.
   The IP address that I have set for the domain is
   I seems to be a DNS setting and some Reverse Lookup Zone thing.... but I can't be sure. Hope that you can help.

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David WilhoitSenior Consultant, ExchangeCommented:
you've got your private IP address published publicly, that's the misery. You must be running your own public DNS, and your internal IP address got registered. Go into the IP configuration, and uncheck that box, "register this connection's address in DNS"

The problem is that the recipient's mail server likely has an anti-virus package (or the Exchange switch flipped) that performs reverse DNS lookups.  It does not appear that is a registered sub-domain of does not show a listing for at all.  Assuming that .my is Malaysia, the holder of the domain would need to list as a subdomain and setup MX records for you.  DNSStuff does show a listing for, but does not show any A records (or MX records), etc.  It may be that this is your domain.

You will need to configure your external DNS servers as well as the internal servers to host the proper domain.  If you own, then you will need to either create a DOA (Delegate of Authority) to the domain.  If you do not own, then you will need to change your recipient policy in Exchange to send/recieve

Note:  If you own and, then you will need to make a decision on what domain to use as your primary.  You can also setup recipient policies so that some users send out and others send out  It's all in the recipient policy config.  You can not, however, use unless you own

Second: As a design consideration, it is always a bad idea to co-lo Exchange and Active Directory on the same server.  I always have to mention that...but small environments do not always have the luxury to follow best practices and have multiple servers.  Microsoft does make an SBS package as well.
It's also bad to directly expose your Active Directory environment and internal DNS to the Internet.
I double-checked.  Your MX shows an internal address and an external addres.  I would suggest setting up your external DNS so that it does not show an internal IP.  There are probably several inexpensive malaysian DNS services that will host your external DNS.

> set type=mx
Server:  []
Address:       MX preference = 10, mail exchanger = othellomx.ntsoftwar     internet address =     internet address =
waimingAuthor Commented:
Hi all,
    The mails will go out to any other domain or any other email addresses except for this particular domain:
    The error that occurred is as I have mentioned. Microsoft says nothing about that error though.
    Kidego, I have unchecked "register this connection's address in DNS" but to no avail.
   Please advise.
   Thanx and really appreciate this.

David WilhoitSenior Consultant, ExchangeCommented:
Well, you need to remove the public DNS records from your AD, this is really bad practice, as flyguybob mentioned. How soon can you get another DNS server up; just a box with W2K3 and DNS? This would host your public records, and this needs to happen fairly soon.

As you can see, lots of issues with your DNS. If you can't build a new server, you need to build a separate primary DNS zone for, holding only the external IP addresses. But in reality, get a new box for external DNS or have someone host your DNS (better idea)


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