"Sender domain in DNS?

Ye' old general discussion board. Basically, for everything that isn't covered elsewhere. Come here to shoot the breeze, shoot your mouth off, or whatever suits your fancy.
This forum is not for asking programming related questions.

Moderator: General Moderators

Post Reply
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

"Sender domain in DNS?

Post by Bill H »

This error is not one I'm familiar with. (Email not sent.)
5.4.7 - Delivery expired (message too old) [Default] 450-'4.4.1 Sender domain not found in DNS' <<...>>
Both the sender's and recipient's email address's are valid, but why does the sender's domain need to be found in the DNS?
User avatar
Chris Corbyn
Breakbeat Nuttzer
Posts: 13098
Joined: Wed Mar 24, 2004 7:57 am
Location: Melbourne, Australia

Post by Chris Corbyn »

Many MTA's will do a lookup of the domain because spammer will commonly try using fake addresses. You can probably turn that feature off but I wouldn't advise it...
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

Except that the sending domain is entirely legitimate. (My client is the sender.)
The recipient is a .mil address.
(What is an "MTA"?)
User avatar
regX
Forum Newbie
Posts: 23
Joined: Thu May 10, 2007 9:33 am
Location: USA

Post by regX »

MTA=Mail Transport/Transfer Agent

Depends on the server...Rockcliffe calls it "Transport", but I think "Transfer" is technically correct.

From looking at the error it looks like your email server is trying to resolve the hostname and can't. Your clients might have a botched DNS zone record. Try using DNS Report to help diagnose the problem.

Doesn't your email server support a whilelist? By adding the domain to a whitelist it should bypass whatever security is causing the error (reverse dns lookup probably).
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

Okay, I'm confused. Whose mail server is "trying to resolve" and to whose mail server's whitelist should what email address be added? My client sends emails to hundreds (literally hundreds) of people and none of them get bounced, except to this one address.

Neither address is mine - I am not involved here except that my client has asked me for advice. I do some php/mysql programming and I know only a little about servers and absolutely nothing about email protocols. My client's server is shared hosting, so there is very little control of the workings thereof. The recipient's email address ends in ".mil" so I rather assume it is a military server and I kind of doubt the user is going to have much control of it either.

My experience is that email is becoming less and less useful as a means of communication, and this may simply be one more step in that direction?
User avatar
RobertGonzalez
Site Administrator
Posts: 14293
Joined: Tue Sep 09, 2003 6:04 pm
Location: Fremont, CA, USA

Post by RobertGonzalez »

Client, like customer, or client, like Email client (Outlook, Thunderbird, etc)?

Is someone actually typing in the address into their email client and sending, then getting a bounce report? Or is this a web app that is bouncing the mails? Are the mails actually bouncing or are you just getting a report of the message?
User avatar
Chris Corbyn
Breakbeat Nuttzer
Posts: 13098
Joined: Wed Mar 24, 2004 7:57 am
Location: Melbourne, Australia

Post by Chris Corbyn »

Ok, basically, whatever mail server (SMTP server) you contact to send these emails is trying to lookup the hostname of the sender's address. It's (probably) not the SMTP software's fault but it is unable to resolve a MX record for the domain name. That therefore suggests that the DNS servers the SMTP software is contacting are not returning the IP. That information is configured in the operating system in /etc/resolv.conf. Basically you need to contact the UNIX admins for the SMTP server ask if they are above to resolve the MX record for the domain which is causing the problem.

Whitelists are equally held on the SMTP server itself. Blacklists can be too.

One thing to bear in mind... mail passes through at least two servers to get to it's intended recipient's mailbox over the internet. Usually it will be relayed through several servers before it gets there. Any one of those servers could have similar issues to what you're experiencing now and sadly, if they do have problems there's not much you can do about it.

To summarise... there's a problem with how the SMTP server is resolving MX records.
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

The client is a customer, small company, for whom I do some programming. They are typing the address into Outlook or Outlook Express (I think the former) and typing the message and clicking the "send" button. They use dsl, and the smtp server is SBC which is not optional - SBC requires them to use that. The "reply to" address is a domain name which is on a shared host, but if Outlook is set up to use that host as the smtp server no mail at all gets sent because SBC blocks it. Ovbiously they don't want to use an SBC address as the "reply to" because they have a domain name which is important to them.

If they call SBC tech support they get someone in India who speaks almost no English and wants them to put their Windows CD into their computer and reinstall Windows, which is why they asked me for help. So, d11wtq, "contacting the UNIX admins" for SBC doesn't seem like an option.

The part that's baffling me, is there a reason that the SBC server would be problematic only for one destination address?
User avatar
RobertGonzalez
Site Administrator
Posts: 14293
Joined: Tue Sep 09, 2003 6:04 pm
Location: Fremont, CA, USA

Post by RobertGonzalez »

It is not going to be the SBC server (I use that at home and sometimes through Yahoo with no problem). I think it is along the lines of what d11 said in that somewhere some server's DNS is not resolving the recipient domain name information properly.
User avatar
phppage
Forum Contributor
Posts: 126
Joined: Mon Apr 24, 2006 1:47 pm
Location: West Yorkshire, UK

Post by phppage »

How long has this been an issue? Have you made any MX record changes recently? You can normally identify at which point it is getting stuck from which server sent the SMTP error. You can then normally contact the administrator of that server either the recipient or ISP and ask them to refresh their DNS. They should refresh at least every 48 hours but have seen it go for weeks before.
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

Yeah, I was leaning away from the SBC server since all emails are sending okay except to this one address. Thanks for the confirmation.

The problem, apparently, is ever since they started trying to send emails to this person. This is a new person for them, and from day one of trying to send to her it has been problematic. I'm still thinking it's a spam filter, but the recipient denies they have one. I think the recipient is full of it, since the server is a military address and I can't imagine a military server without a spam filter and I can easily picture the Marine Corps not having a real good handle on how to set up such a filter properly. (I'm ex-Navy.) The recipient claims, however, that no email in history has ever failed to reach her, so...
User avatar
RobertGonzalez
Site Administrator
Posts: 14293
Joined: Tue Sep 09, 2003 6:04 pm
Location: Fremont, CA, USA

Post by RobertGonzalez »

Bill H wrote:The recipient claims, however, that no email in history has ever failed to reach her, so...
Can you test that theory by sending her a few from various addresses?
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

Can you test that theory by sending her a few from various addresses?
Would that I could.

My client (customer) at my suggestion has asked their client for permission to contact the isp and the person admitted that the isp (a military unit) is "really awful and would probably not respond." Does that give us a hint?

The unfortunate thing is that even though my client's client admits her isp is "really awful" she still more or less blames my client.

Happily my client has been with me for a long time and is now finally accepting that since they can send emails to hundreds of other addresses without problems there is probably nothing wrong with anything "at home." They panic easily but I am usually able to reassure them in the end. (Or, of course, fix the problem.)
User avatar
phppage
Forum Contributor
Posts: 126
Joined: Mon Apr 24, 2006 1:47 pm
Location: West Yorkshire, UK

Post by phppage »

Bill H wrote: I'm still thinking it's a spam filter, but the recipient denies they have one
It's not common for modern day spam filtering systems to reject mail as an SMTP error. If you can't get in touch with the recipients ISP then you are stuffed. Have had similar issues with this before with big National government organisations. They won't give you a lot of their time.

Just wondering and apologies if someone else has asked this before in this thread but if you perform a reverse DNS lookup for the IP address that you are sending your mail from dose it resolve to the correct domain.
User avatar
Bill H
DevNet Resident
Posts: 1136
Joined: Sat Jun 01, 2002 10:16 am
Location: San Diego CA
Contact:

Post by Bill H »

...reverse DNS lookup for the IP address that you are sending your mail from dose it resolve to the correct domain.
I'm not sure what this means, i.e. whether or not this is the "correct domain" or, of not, what the cause and/or result might be.

The email client account server is defined as smtp.sbcglobal.yahoo.com, the isp is SBC dsl (PacBell I believe is the local company) and the result of the reverse DNS lookup is (with numbers okay but removed here for security) "ppp-xx-xxx-xx-x.dsl.sndg02.pacbell.net" top level domain "pacbell.net"

That all looks okay to me, but I'll pass it by guys with higher foreheads than mine for check.
Post Reply