NDR -- Domain does not exist

[keithmyers]

I'm receiving complaints from my users that they are receiving an NDR when they know the remote address to be correct. They all have the same NDR, which is below. I think this might be a DNS issue... Does anyone have any insight? Thanks.

-Keith-

Your message did not reach some or all of the intended recipients.

Subject:
Sent: 2/28/2003 8:08 PM

The following recipient(s) could not be reached:

'user@cfl.rr.com' on 2/28/2003 8:09 PM
The e-mail address could not be found. Perhaps the recipient moved to a different e-mail organization, or there was a mistake in the address. Check the address and try again.
<EXCHANGESERVER.mydomain.com #5.1.8 smtp;553 5.1.8 <user@mydomain.com <mailto:user@mydomain.com>>... Domain of sender address user@mydomain.com <mailto:user@mydomain.com> does not exist>

 

[wyzard]

Hi,

Referencing the 5.1.8 error code, basically the SENDERS address does not exist in DNS. Which is a little strange since you (your company) has an email domain. It almost sounds as if there is a relay issue.

Are you relaying through a provider for email delivery?

This is the first time I've seen this error, so I am just guessing what the problem might be at this point.

Wyz

 

[keithmyers]

I'm not relaying through anyone.

It looks like the remote host is doing a DNS lookup and not seeing my domain and refusing the message?!? Maybe cfl.rr.com is having a DNS problem...

-Keith-

 

[wyzard]

Hi again,

Is your MX record showing your actual email namespace or something different?

It sounds as if they have reverse DNS lookup enabled and that possibly their DNS server is not working properly.

Sounds as if you might be on the right track.

Wyz

 

[keithmyers]

The MX record is correct. If it wasn't, I wouldn't be receiving mail... I'll contact cfl.rr.com (Road Runner).

Thanks
-Keith-

 

[wyzard]

Outstanding!

I actually meant to pull out the MX part, and didn't (I got distracted, oops!).

Wyz

 

[itsisnofun]

Make sure your hosting isp has a reverse dns lookup for your domain name. If not some companys will reject email to try to cut down spam coming into the servers. i don't know what the difference is but we seen this problem when we changed form 5.5 to 2000.

 

[keithmyers]

Ok. I thought this was isolated to one remote domain (cfl.rr.com), however, I am receiving reports of the same intermittent problem with other domains. I've searched all over the place for an explanation and still have nothing.

Anyone have any insight?

Thanks
-Keith-

 

[robbyb]

Had something a little like this once. It was intermittent, and with well known domains at that (but only one or two). Turned out that if a message routed out via a certain server on its hops, then that particular server would reject the mail.

We found this out by looking at where the NDR messages were coming from on one of our gateway servers.

You may be able to find a common server in the headers from your NDR's, if there are any headers.

Messages can go via different SMTP server on its way to its destination. When these messages went via this particular server, it resulted in NDR's. We contacted the owner of that server and I imagine they sorted out their DNS, and all was well.

I don't know if you have a backup ISP you could try routing through to see what diff that might make? Otherwise you might speak to your present ISP: if you forward to one of their servers they may have logs they can check to see what's going on. If messages are leaving your domain OK, perhaps see if they can investigate from their end..?

Good Luck,

RobbyB

 

[keithmyers]

Thanks. I realized yesterday that this might be a problem as well:

My internal active directory domain name is different than my email domain name. The AD domain name doesn't really exist to the outside world. Should it?

-Keith-

 

[robbyb]

No, that's OK. As long as your email domain is known to the outside world in DNS. This would mean that you have had to be specific and define your domain to stuff like your SMTP Connector and your Recipient Policies.

But all is well because you are receiving messages OK?

 

[keithmyers]

Yeah, I've been sending/receiving fine (except for the intermittent problem of course) ever since I deployed Exchange. I think I'll open a ticket with my ISP to make sure that their DNS is configured correctly. I'm grasping at straws here...

Thanks
-Keith-

 

[robbyb]

Good Luck - let us know!

 

[keithmyers]

The reverse record was configured strangely. It was x.x.x.x.domain.com. (x=IP address) Should be mail.domain.com. I had my ISP change it, so hopefully this will resolve the situation. I'll know in a few days.

-Keith-