CNAME lookup failed temporarily. (#4.4.3) bounced emails

[Lisa Kachold]

Keith,

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
>

Does the IP address of this server match the sending domain?
Do you have both a forward and reverse DNS record for that IP?
Does the domain have a MX record?

Since you are sending from a php scripted header, many of these automatic
checks of mail to identify SPAM might not be automatically passed.

One of the big ones that gets a server flagged is the dynamic nature of the
mail server.  I.E. it's reverse IP resolves as swipped to the hoster or the
bandwidth provider as "dynamic".

You are correct that a TXT DNS SPF (sender policy frameword) record might
help here (as discussed in other email).

Asking whoever provided your IP to also enter a reverse DNS entry alias
that matches your server domain might assist.

You can check your IPaddress "send score" here:
https://www.senderscore.org/

Of course as was already mentioned, be certain that you have not already
been flagged for spam and your server is secure.

Most of the big mail systems (including commercial types) use the same
rules as spamassassin!

The content of your email could contain some of the watchwords that push it
over the edge to "reject":

http://www.contactology.com/check_mqs.php

The full email header and content from their server will assist you to see
why it's being refused; send a command line sendmail debug to see why the
server is denying it:

/sbin/sendmail -d testemail at comcast.com
sometext
.
.
<wait for output>

or pipe it to output:

/sbin/sendmail -d testemail at comcast.com >/tmp/testemail
sometext
.
.
more /tmp/testemail

You can test your mail's deliverability in various test tools:
http://www.emailreach.com/





> 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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