Client host rejected: rDNS/DNS validation failed

R

rszkutak

Verified User
Joined
Dec 22, 2003
Messages
173
Location
Scottsdale, AZ & Clam Gulch, AK
Here is something interesting, a few of my hosting clients are trying to post or reply on craigslist and are getting these bounce messages. Has anyone seen this before or know how to fix it ?

The IP that the host is replying to is indeed my shared IP for the system which the vast majority of my customers ride on, but this is as clear as mud. My Co-Lo Facility has a genaric RDNS entry in their system for the block of IP's that are assigned to me, but i cannot create hundreds of RDNS zones, one for each customer...

Thoguths ?

thanks,
Rob



This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

[email protected]
SMTP error from remote mailer after RCPT
TO:<[email protected]>:
host mxi3s.craigslist.org [66.150.243.3]: 554 <unknown[64.207.216.20]>:
Client host rejected: rDNS/DNS validation failed. Please setup matching DNS and rDNS records:
http://bind8nt.meiway.com/itsaDNSmess.cfm
 
Without you telling us your hostname any response would be a guess.

Look here to see why you shouldn't obscure your data when asking for help.

Jeff
 
jeff,
I didn't leave anything out of the message at all, everything i got was in that message. I don't mask anything as i know it's difficult to diagnose a DNS problem with only part of the picture.

my dns on the server is bluenetworking.com


Thanks,
Rob
 
not quite sure... whatever DA sets it to. The only thing i did to EXIM was set the IP address that mail came from.

how could i get the hostname for you ? of course if i telnet to the server on port 25, it does't show anything.

the mail server is mail.bluenetworking.com


Rob
 
I believe that is your problem. Change your server name to something like da.youname.com or secure.yourname.com. Also, make sure that the yourname.com DNS zone has an A record so your hostname resolves.
 
Jeremy,

it shouldn't matter what the hostname actually is; it can be anything that's not a DA domain name.

rszkutak,

Your settings really should work for any mail client, but evidently CraigsList wants the reverse DNS to point to the forward DNS.

My guess (since I don't know what CraigsList does) is that your rDNS and DNS for 64.207.216.20 must point to the same thing.

For example:
Code: 
nslookup 64.207.216.20
returns unused.mynethost.com, but
Code: 
nslookup unused.mynethost.com
returns 64.207.205.207.
Since your host can't change the IP# for unusued.mynethost.com, they'll probably have to change the reverse DNS for 64.207.216.20 to something you tell them (something with an A record pointing to 64.207.216.20.

This will probably solve the problem.

Jeff
 
You're welcome, Rob. You're welcome, Jeremy :) .

Rob, please let us know as you resolve this; it's an interesting issue.

Thanks.

Jeff
 
I have the same issue.

I have a customer running on his own dedicated ip. But the mail is send out on the main ip, with the shared server/domain name.

If you run it through DNSreport.com it warns on:

Mail server host name in greeting

WARNING: One or more of your mailservers is claiming to be a host other than what it really is (the SMTP greeting should be a 3-digit code, followed by a space or a dash, then the host name). If your mailserver sends out E-mail using this domain in its EHLO or HELO, your E-mail might get blocked by anti-spam software. This is also a technical violation of RFC821 4.3 (and RFC2821 4.3.1). Note that the hostname given in the SMTP greeting should have an A record pointing back to the same server. Note that this one test may use a cached DNS record.
 
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