Keith,<br><br><div class="gmail_quote">On Wed, Nov 21, 2012 at 4:50 PM, keith smith <span dir="ltr"><<a href="mailto:klsmith2020@yahoo.com" target="_blank">klsmith2020@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p style="margin-bottom:0in">Hi,</p>
<p style="margin-bottom:0in"><br>
</p>
<p style="margin-bottom:0in">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</p></td></tr></tbody></table></blockquote><div><br></div><div>Does the IP address of this server match the sending domain?</div>
<div>Do you have both a forward and reverse DNS record for that IP?</div><div>Does the domain have a MX record?</div><div><br></div><div>Since you are sending from a php scripted header, many of these automatic checks of mail to identify SPAM might not be automatically passed.</div>
<div><br></div><div>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". </div>
<div><br></div><div>You are correct that a TXT DNS SPF (sender policy frameword) record might help here (as discussed in other email).</div><div><br></div><div>Asking whoever provided your IP to also enter a reverse DNS entry alias that matches your server domain might assist. </div>
<div><br></div><div>You can check your IPaddress "send score" here: <a href="https://www.senderscore.org/">https://www.senderscore.org/</a></div><div><br></div><div>Of course as was already mentioned, be certain that you have not already been flagged for spam and your server is secure.</div>
<div><br></div><div>Most of the big mail systems (including commercial types) use the same rules as spamassassin!</div><div><br></div><div>The content of your email could contain some of the watchwords that push it over the edge to "reject":</div>
<div><br></div><div><a href="http://www.contactology.com/check_mqs.php">http://www.contactology.com/check_mqs.php</a></div><div><br></div><div>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:</div>
<div><br></div><div>/sbin/sendmail -d <a href="mailto:testemail@comcast.com">testemail@comcast.com</a></div><div>sometext </div><div>.</div><div>.</div><div><wait for output></div><div><br></div><div>or pipe it to output:</div>
<div><br></div><div><div>/sbin/sendmail -d <a href="mailto:testemail@comcast.com">testemail@comcast.com</a> >/tmp/testemail</div><div>sometext </div><div>.</div><div>.</div><div>more /tmp/testemail</div></div><div><br>
</div><div>You can test your mail's deliverability in various test tools:</div><div><a href="http://www.emailreach.com/">http://www.emailreach.com/</a></div><div><br></div><div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p style="margin-bottom:0in">These emails are sent directly from the
box, such as the order confirmation email.</p>
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</p>
<p style="margin-bottom:0in">The problem started when we upgraded
from CentOS 5.x to CentOS 6.x. I wonder if anyone else has
experience this problem.</p>
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</p>
<p style="margin-bottom:0in">The failure message: <br><br>> Hi.
This is the qmail-send program at [boxes fully qualified domain
name]. <br>> I'm afraid I wasn't able to deliver your message to
the following <br>addresses. <br>> This is a permanent error; I've
given up. Sorry it didn't work out. <br>> <br>> <a href="mailto:MEUSTACE2@COMCAST.NET" target="_blank">[</a>customers
email address]: <br>> CNAME lookup failed temporarily. (#4.4.3)
I'm not going to try again; <br>> this message has been in the
queue too long. <br><br>Only happens when emails are sent to Comcast
directly from the server - order confirmation and shipping
confirmation. <br><br>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??<br></p>
<p style="margin-bottom:0in"><br>
</p>
<p style="margin-bottom:0in">Is this true or could it be another
issue?
</p>
<p style="margin-bottom:0in"><br>
</p>
<p style="margin-bottom:0in">Thank you for your feedback!</p>
<p style="margin-bottom:0in"><br>Keith
</p>
<br><br><br>------------------------<br>
Keith Smith</td></tr></tbody></table><br>---------------------------------------------------<br>
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