CNAME lookup failed temporarily. (#4.4.3) bounced emails

[JD Austin]

Check that your server is not on any RBL list (real time black hole list).
Alternately set up a smart host to send through a provider they don't block
(like gmail/google apps for domains).
You can test manually using telnet.
First get their mail exchange records:

nslookup -query=MX comcast.com

Server:      x.x.x.x

Address: y.y.y.y#53


Non-authoritative answer:

comcast.com mail exchanger = 5 mx1.comcast.com.

comcast.com mail exchanger = 5 mx2.comcast.com.

comcast.com mail exchanger = 5 mx3.comcast.com.

comcast.com mail exchanger = 5 mx4.comcast.com.


Authoritative answers can be found from:

comcast.com nameserver = dns101.comcast.net.

comcast.com nameserver = dns102.comcast.net.

comcast.com nameserver = dns103.comcast.net.

comcast.com nameserver = dns104.comcast.net.

comcast.com nameserver = dns105.comcast.net.

mx1.comcast.com internet address = 76.96.32.247

mx2.comcast.com internet address = 76.96.32.252

mx3.comcast.com internet address = 69.241.43.117

mx4.comcast.com internet address = 69.241.43.118


telnet 76.96.32.24 25
helo <your server name>
mail from:< <from%3Aroot at san.mesacc.edu>user>@<your server name>
rcpt to:<user2>@c <to%3Asean.parsons at mesacc.edu>omcast.com
This is a test email
.


On Wed, Nov 21, 2012 at 4:50 PM, keith smith <klsmith2020 at yahoo.com> wrote:

>
> Hi,
>
>
>  One of the Vhost on a server I run is a shopping cart. We have been
> experiencing bounced emails when sending to Comcast. We do not have this
> problem with any other ISP.
>
>
>  These emails are sent directly from the box, such as the order
> confirmation email.
>
>
>  The problem started when we upgraded from CentOS 5.x to CentOS 6.x. I
> wonder if anyone else has experience this problem.
>
>
>  The failure message:
>
> > Hi. This is the qmail-send program at [boxes fully qualified domain
> name].
> > I'm afraid I wasn't able to deliver your message to the following
> addresses.
> > This is a permanent error; I've given up. Sorry it didn't work out.
> >
> > [ <MEUSTACE2 at COMCAST.NET>customers email address]:
> > CNAME lookup failed temporarily. (#4.4.3) I'm not going to try again;
> > this message has been in the queue too long.
>
> Only happens when emails are sent to Comcast directly from the server -
> order confirmation and shipping confirmation.
>
> I've search for a solution and read this can be corrected by setting the
> DISABLE_CNAME_LOOKUP in qmail-remote.  Something about a buffer being too
> small??
>
>
>  Is this true or could it be another issue?
>
>
>  Thank you for your feedback!
>
>
> Keith
>
>
>
> ------------------------
> Keith Smith
> ---------------------------------------------------
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