Comcast and AOL Email SMTP Errors

I'm running SBS 2003 SP1 Premium and all has been well. For the past month
or so, the users cannot successfully send messages to AOL or Comcast
accounts. My SBS Exchange server will attempt the SMTP connection for
several days and then fail. I am running Exchange 2003 SP2 and my server is
completely updated. I'm using a MX record in my DSN table and I know that my
server is not an open relay--nor is it listed as one. These errors only
occur when sending to these two domains.

Here's the error:

Your message did not reach some or all of the intended recipients.

Subject: FW: Hello

Sent: 3/14/2006 12:37 PM

The following recipient(s) could not be reached:

K. Kametches on 3/14/2006 12:38 PM

There was a SMTP communication problem with the recipient's
email server. Please contact your system administrator.

<gpkflooring.com #5.5.0 smtp;521-EHLO/HELO from sender
69.15.36.74 does not map to gpkflooring.com in DNS>


Thanks.

Ken

It looks to me that Comast and AOL cannot do a reverse DSN lookup on your
emails, as you may have a dynamic IP address. Basically, AOL will try to
verify that the email in effect came from you not a spammer, by attempting a
reverse DNS lookup. If they can do this, they'll accept your mail, otherwise
they will not. Your Exchange server will keep trying to send it until it
times out.

You will need setup a SMARTHOST on your Exchange server. A smarthost will
forward your outgoing messages to a third party like DynDNS.org, and from
there, you message will go out authenticated, and AOL cant trace it back to
them. To get around this problem, I use DynDNS.org.
Check out this link from Javier Gomez, it will explains this in detail:
http://www.sbslinks.com/DNS_Smarthost.htm

Attila

"shepcon" <shepcon@discussions.microsoft.com> wrote in message
news:A2466B77-BEEC-4ACD-B789-6B4EE544FCBD@microsoft.com...
> I'm running SBS 2003 SP1 Premium and all has been well. For the past
> month
> or so, the users cannot successfully send messages to AOL or Comcast
> accounts. My SBS Exchange server will attempt the SMTP connection for
> several days and then fail. I am running Exchange 2003 SP2 and my server
> is
> completely updated. I'm using a MX record in my DSN table and I know that
> my
> server is not an open relay--nor is it listed as one. These errors only
> occur when sending to these two domains.
>
> Here's the error:
>
> Your message did not reach some or all of the intended recipients.
>
> Subject: FW: Hello
>
> Sent: 3/14/2006 12:37 PM
>
> The following recipient(s) could not be reached:
>
> K. Kametches on 3/14/2006 12:38 PM
>
> There was a SMTP communication problem with the recipient's
> email server. Please contact your system administrator.
>
> <gpkflooring.com #5.5.0 smtp;521-EHLO/HELO from sender
> 69.15.36.74 does not map to gpkflooring.com in DNS>
>
>
> Thanks.
>
> Ken

Actually, I'm running a static IP address. I do also support about a dozen
other SBS installs and this has been quite consistent, especially with AOL.
I do know about reverse DNS as a form of spam prevention, but my SBS installs
are standard and all updated.

"Attila Csokai" wrote:

> It looks to me that Comast and AOL cannot do a reverse DSN lookup on your
> emails, as you may have a dynamic IP address. Basically, AOL will try to
> verify that the email in effect came from you not a spammer, by attempting a
> reverse DNS lookup. If they can do this, they'll accept your mail, otherwise
> they will not. Your Exchange server will keep trying to send it until it
> times out.
>
> You will need setup a SMARTHOST on your Exchange server. A smarthost will
> forward your outgoing messages to a third party like DynDNS.org, and from
> there, you message will go out authenticated, and AOL cant trace it back to
> them. To get around this problem, I use DynDNS.org.
> Check out this link from Javier Gomez, it will explains this in detail:
> http://www.sbslinks.com/DNS_Smarthost.htm
>
> Attila
>
> "shepcon" <shepcon@discussions.microsoft.com> wrote in message
> news:A2466B77-BEEC-4ACD-B789-6B4EE544FCBD@microsoft.com...
> > I'm running SBS 2003 SP1 Premium and all has been well. For the past
> > month
> > or so, the users cannot successfully send messages to AOL or Comcast
> > accounts. My SBS Exchange server will attempt the SMTP connection for
> > several days and then fail. I am running Exchange 2003 SP2 and my server
> > is
> > completely updated. I'm using a MX record in my DSN table and I know that
> > my
> > server is not an open relay--nor is it listed as one. These errors only
> > occur when sending to these two domains.
> >
> > Here's the error:
> >
> > Your message did not reach some or all of the intended recipients.
> >
> > Subject: FW: Hello
> >
> > Sent: 3/14/2006 12:37 PM
> >
> > The following recipient(s) could not be reached:
> >
> > K. Kametches on 3/14/2006 12:38 PM
> >
> > There was a SMTP communication problem with the recipient's
> > email server. Please contact your system administrator.
> >
> > <gpkflooring.com #5.5.0 smtp;521-EHLO/HELO from sender
> > 69.15.36.74 does not map to gpkflooring.com in DNS>
> >
> >
> > Thanks.
> >
> > Ken
>
>
>

shepcon wrote:
> I'm running SBS 2003 SP1 Premium and all has been well. For the past month
> or so, the users cannot successfully send messages to AOL or Comcast
> accounts. My SBS Exchange server will attempt the SMTP connection for
> several days and then fail. I am running Exchange 2003 SP2 and my server is
> completely updated. I'm using a MX record in my DSN table and I know that my
> server is not an open relay--nor is it listed as one. These errors only
> occur when sending to these two domains.
>
> Here's the error:
>
> Your message did not reach some or all of the intended recipients.
>
> Subject: FW: Hello
>
> Sent: 3/14/2006 12:37 PM
>
> The following recipient(s) could not be reached:
>
> K. Kametches on 3/14/2006 12:38 PM
>
> There was a SMTP communication problem with the recipient's
> email server. Please contact your system administrator.
>
> <gpkflooring.com #5.5.0 smtp;521-EHLO/HELO from sender
> 69.15.36.74 does not map to gpkflooring.com in DNS>
>
>
> Thanks.
>
> Ken


Comcast has made a big policy change on thier email servers starting
around March 1st. They require you have a reverse dns entry put in.
You will have to register this with your ISP. If you have a T1, just
call up the provider and have them put an rDNS entry for the IP which
you are sending from to have a match to what ever you are bannering.

ie. If you are email servers says HELO/EHLO smtpout.domain.com and
your external IP address is x.x.x.x then you need to have them put
smtpout.domain.com on that IP.

Also, since you are getting blocked right now, you may have to go the
next step and have them remove you from a blocklist after it is fixed.

I send an email to 'blacklist_comcastnet@cable.comcast.com'

smtp banner = smtpout.domain.com



Domains this affects
domain.com x.x.x.x (your rdns ip)

MX Records
domain.com. MX IN 10 airmail.domain.com. [Preference =
10]
domain.com. MX IN 10 airmail2.domain.com. [Preference =
20]
domain.com. MX IN 10 smtpout.domain.com. [Preference =
30]

A Records
airmail.domain.com. A IN 10
x.x.x.x1
airmail2.domain.com. A IN 10
x.x.x.x2
smtpout.domain.com. A IN 10
x.x.x.x52 (numbers just to show they are different

PTR Records
252.232.x.x.in-addr.arpa. PTR IN 3600
smtpout.domain.com.
234.159.x.x.in-addr.arpa. PTR IN 7200
airmail.domain.com.

rDNS
x.x.x.x PTR record: smtpout.domain.com. [TTL 3600s] [A=x2.x1.x2.x2]
x.x.x.x PTR record: airmail.domain.com. [TTL 7200s] [A=x4.x2.x9.x4]
x8.x0.x0.x0 PTR record: airmail2.domain.com. [TTL 86400s]
[A=x8.x0.x0.x0]


Ok...feel like I am rambling...anyway...I used dnsstuff.com to get a
lot of my results fairly quickly.

I feel like I am missing something, but this should give you a head
start. Also, remember that if you change IP info on the internet, it
can take 24-48 hours to propigate.

Thanks, Pat. I've added the necessary reverse PTR record to my DNS table.

"pat.stiller@gmail.com" wrote:

> shepcon wrote:
> > I'm running SBS 2003 SP1 Premium and all has been well. For the past month
> > or so, the users cannot successfully send messages to AOL or Comcast
> > accounts. My SBS Exchange server will attempt the SMTP connection for
> > several days and then fail. I am running Exchange 2003 SP2 and my server is
> > completely updated. I'm using a MX record in my DSN table and I know that my
> > server is not an open relay--nor is it listed as one. These errors only
> > occur when sending to these two domains.
> >
> > Here's the error:
> >
> > Your message did not reach some or all of the intended recipients.
> >
> > Subject: FW: Hello
> >
> > Sent: 3/14/2006 12:37 PM
> >
> > The following recipient(s) could not be reached:
> >
> > K. Kametches on 3/14/2006 12:38 PM
> >
> > There was a SMTP communication problem with the recipient's
> > email server. Please contact your system administrator.
> >
> > <gpkflooring.com #5.5.0 smtp;521-EHLO/HELO from sender
> > 69.15.36.74 does not map to gpkflooring.com in DNS>
> >
> >
> > Thanks.
> >
> > Ken
>
>
> Comcast has made a big policy change on thier email servers starting
> around March 1st. They require you have a reverse dns entry put in.
> You will have to register this with your ISP. If you have a T1, just
> call up the provider and have them put an rDNS entry for the IP which
> you are sending from to have a match to what ever you are bannering.
>
> ie. If you are email servers says HELO/EHLO smtpout.domain.com and
> your external IP address is x.x.x.x then you need to have them put
> smtpout.domain.com on that IP.
>
> Also, since you are getting blocked right now, you may have to go the
> next step and have them remove you from a blocklist after it is fixed.
>
> I send an email to 'blacklist_comcastnet@cable.comcast.com'
>
> smtp banner = smtpout.domain.com
>
>
>
> Domains this affects
> domain.com x.x.x.x (your rdns ip)
>
> MX Records
> domain.com. MX IN 10 airmail.domain.com. [Preference =
> 10]
> domain.com. MX IN 10 airmail2.domain.com. [Preference =
> 20]
> domain.com. MX IN 10 smtpout.domain.com. [Preference =
> 30]
>
> A Records
> airmail.domain.com. A IN 10
> x.x.x.x1
> airmail2.domain.com. A IN 10
> x.x.x.x2
> smtpout.domain.com. A IN 10
> x.x.x.x52 (numbers just to show they are different
>
> PTR Records
> 252.232.x.x.in-addr.arpa. PTR IN 3600
> smtpout.domain.com.
> 234.159.x.x.in-addr.arpa. PTR IN 7200
> airmail.domain.com.
>
> rDNS
> x.x.x.x PTR record: smtpout.domain.com. [TTL 3600s] [A=x2.x1.x2.x2]
> x.x.x.x PTR record: airmail.domain.com. [TTL 7200s] [A=x4.x2.x9.x4]
> x8.x0.x0.x0 PTR record: airmail2.domain.com. [TTL 86400s]
> [A=x8.x0.x0.x0]
>
>
> Ok...feel like I am rambling...anyway...I used dnsstuff.com to get a
> lot of my results fairly quickly.
>
> I feel like I am missing something, but this should give you a head
> start. Also, remember that if you change IP info on the internet, it
> can take 24-48 hours to propigate.
>
>