Re: Comcast Email Problems

For those of you who are interested in this, it's important for us to
understand the difference between our dns and reverse dns. I don't totally
understand it yet, but I'm working on it. And I think that up until now
lot's of domains have been lax on it and that's why we haven't had problems
up until now.

Our ISP (your actual "bandwidth" provider) needs to have reverse dns entries
set up IN ADDITION TO our domain registrars having our dns setup. Please
correct me if I'm wrong here. They need to be both properly set up in order
for us to say, "our dns is set up properly".

I've had my ISP set up a PTR entry for our reverse dns lookup and it appears
so far to have worked!

I haven't had to touch anything on our end so far.

Again, some guru here please correct me if I'm wrong here.

Bryce.


""Jenny wu [MSFT]"" <v-yanniw@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:mqsLSm$SGHA.4820@xxxxxxxxxxxxxxxxxxxxxxxx
Hi Roger,

Thanks for your input.

I am sorry for the unavailable link. Many Microsoft KB articles have been
re-compiled or integrated with another editions KB articles, so some links
may disappear. I am sorry for bring your inconvenience.

You can check the article: Telnet to Port 25 to Test SMTP Communication in
the following link:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;153119

Please let me know if you have question to the issue. I am happy to be of
assistance to you.

Have a nice day!

Sincerely,

Jenny Wu
Microsoft CSS Online Newsgroup Support
Get Secure! - www.microsoft.com/security
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--------------------
From: "R" <none@xxxxxxxx>
References: <elMv$u9QGHA.5296@xxxxxxxxxxxxxxxxxxxx>
<D122699B-A969-4D10-8D59-94BCDD01EBCF@xxxxxxxxxxxxx>
<OyHz#LMSGHA.5908@xxxxxxxxxxxxxxxxxxxx>
<A39611EE-297D-4E6B-830D-9C89D6704C7A@xxxxxxxxxxxxx>
<b52JDXYSGHA.7480@xxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Comcast Email Problems
Date: Fri, 17 Mar 2006 08:46:33 -0600
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The Knowledge Base (KB) Article You Requested Is Currently Not Available
that is the response I get on sooo many links to microsoft support
recently.

Roger.

""Jenny wu [MSFT]"" <v-yanniw@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:b52JDXYSGHA.7480@xxxxxxxxxxxxxxxxxxxxxxxx
Hi Tony,

Thanks for using the SBS newsgroup.

From your description, I understand that you have problem to send email
to
Comcast. If I am off base, please don't hesitate to let me know.

Before we go any further, please kindly help me collect some information
to
isolate the issue:

1. Can you receive a NDR from the Comcast? What is the exact message
content of the NDR? Please save one NDR to .msg format and mail to me.
My
working mailbox: v-yanniw@xxxxxxxxxxxxx

2. Do you have other problem to send emails to other external email
domain?

3. Please use telnet command to try to send email to Comcast.com and
copy
the output for me for analyze. Please refer to the KB 838049 to process:

838049 HOWTO: Telnet to Port 25 to Test SMTP Communication
http://support.microsoft.com/?id=838049

4. Please let me know the following information of your domain so that
we
can check if the configuration is correct:

a. the public IP address and public FQDN of your server box
b. your email domain
c. Please run command "ipconfig /all" (no quotation marks) on the server
box and mail me the output.

Based on my research, the Comcast and many other major mail servers
(such
as AOL) are now blocking mail when they cannot resolve the sending
e-mail
server. AOL is doing reverse DNS lookup on the Exchange/SBS box against
the
recipient's address of the mail. The AOL.com mail server requires that a
valid reverse DNS record (known as PTR) for all of your domain's MX
records. AOL.com also requires that for every inbound SMTP connection,
the
connecting SMTP server must have a valid PTR record even if an MX record
does not exist.

Related information:

554 DNS:B2
http://postmaster.info.aol.com/errors/554dnsb2.html

NOTE: This response contains a reference to a third party World Wide Web
site. Microsoft is providing this information as a convenience to you.
Microsoft does not control these sites and has not tested any software
or
information found on these sites; therefore, Microsoft cannot make any
representations regarding the quality, safety, or suitability of any
software or information found there. There are inherent dangers in the
use
of any software found on the Internet, and Microsoft cautions you to
make
sure that you completely understand the risk before retrieving any
software
from the Internet.

In most cases, we can resolve this issue by routing mail for the
Comcast.com domain through an SMTP connector to a smart host. However,
it
depends that the Smart Host you use is allowed by Comcast.com.

Or, we need to use the following method to resolve this issue (both of
them
needs the cooperation with your ISP):

1. Make sure that your public DNS records that are hosted on your DNS
server are correct. On your DNS server check the following:

a) You must have an MX record for your domain that points to a valid
Host
(A) record. For example, the MX record for <contoso.com> points to
<mail.contoso.com>, which is a valid e-mail server.

b) Make sure that the Host (A) record points to a valid IP Address. For
example, make sure that <mail.yourcompany.com> points to <209.88.88.88>,
which is the correct public IP Address for your e-mail server.

2. For every SMTP or Exchange server that sends outbound Internet mail,
make sure that there is a valid PTR record for the Public IP address of
that sending SMTP or Exchange server. This may be a firewall, router, or
another device that used to publish your domain information to an IP
address that is visible by Internet hosts. For example, If your Exchange
server is behind a firewall with an internal IP of 10.10.10.1, and the
firewall has an external IP of 4.3.2.1. When the Exchange server sends
mail
to AOL.COM through the firewall, the receiving mail server sees that the
4.3.2.1 IP address is connecting for SMTP Communication. The receiving
mail
server performs a reverse DNS lookup against this IP address, not
necessarily the MX record. The AOL mail server must find a PTR for
4.3.2.1
pointing to a valid host record in the <contoso.com> domain.

Hope above information helps! I am happy to be of assistance to you and
look forward to your reply.

Have a nice day!

Sincerely,

Jenny Wu
Microsoft CSS Online Newsgroup Support
Get Secure! - www.microsoft.com/security
======================================================
This newsgroup only focuses on SBS technical issues. If you have issues
regarding other Microsoft products, you'd better post in the
corresponding
newsgroups so that they can be resolved in an efficient and timely
manner.
You can locate the newsgroup here:
http://www.microsoft.com/communities/newsgroups/en-us/default.aspx

When opening a new thread via the web interface, we recommend you check
the
"Notify me of replies" box to receive e-mail notifications when there
are
any updates in your thread. When responding to posts via your
newsreader,
please "Reply to Group" so that others may learn and benefit from your
issue.

Microsoft engineers can only focus on one issue per thread. Although we
provide other information for your reference, we recommend you post
different incidents in different threads to keep the thread clean. In
doing
so, it will ensure your issues are resolved in a timely manner.

For urgent issues, you may want to contact Microsoft CSS directly.
Please
check http://support.microsoft.com for regional support phone numbers.

Any input or comments in this thread are highly appreciated.
======================================================
This posting is provided "AS IS" with no warranties, and confers no
rights.

--------------------
Thread-Topic: Comcast Email Problems
thread-index: AcZJAtG/qvFo7Tq9TfKzNxOAcOd+XQ==
X-WBNR-Posting-Host: 64.252.190.193
From: =?Utf-8?B?VG9ueSBQLg==?= <Tony P.@xxxxxxxxxxxxxxxxxxxxxxxxx>
References: <elMv$u9QGHA.5296@xxxxxxxxxxxxxxxxxxxx>
<D122699B-A969-4D10-8D59-94BCDD01EBCF@xxxxxxxxxxxxx>
<OyHz#LMSGHA.5908@xxxxxxxxxxxxxxxxxxxx>
Subject: Comcast Email Problems
Date: Thu, 16 Mar 2006 06:06:28 -0800
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NNTP-Posting-Host: TK2MSFTNGXA03.phx.gbl 10.40.2.250
X-Tomcat-NG: microsoft.public.windows.server.sbs

I'm having the same exact problem with a client of mine. Can't seem to
find
a fix. And it's only happening with Comcast email accounts as of last
week.








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