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From: John Oliver, Jr. [MVP] on 24 May 2010 17:00
Jeff,

Not using ISP as a Smarthost though. I would always recommend this rather
than using DNS directly for most broadband circuits such as DSL or Cable,
not so much with T1's. In this case, if you choose to stay with DNS you
will have to contact your ISP to see why your IP range is being
blacklisted/blocked by Comcast. Seems that particular range of IP's has
been tagged as potential spammer and you are seeing the indirect
consequences of that. Only way to clear this up is to contact your ISP to
see if this is indeed the case or was the case. I have seen ISP's IP ranges
get blocked/listed and they must initiate the request to other ISP's to
unblock. Let me know how things progress.

--
John Oliver, Jr
MCSE, MCT, CCNA
Exchange MVP 2010
Microsoft Certified Partner


"Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
news:CEF6F1A4-251E-4FA9-8FDC-B5DD170D67E7(a)microsoft.com...
> Our Exchange server has a static IP that was given to us 7 years ago by
> our
> ISP.
> Our ISP manages our DNS (which I can modify any time)
> This is NOT Residential internet service.
>
> We are not doing a relay with our ISP - Everything is static.
>
> Comcast is the only problem we're having.
>
> One thing that may be an issue, which I would like your opinion - Our
> firm's
> signature file in Outlook consists of 3 attachments (graphics files) We
> are
> also sending email as HTML and not plain text.
>
> Thanks for your help so far.
> Jeff
>
>
> "John Oliver, Jr. [MVP]" wrote:
>
>> Jeff,
>>
>> Can you please give some info on your ISP setup? Are you using them as a
>> Smarthost or anyone else for that matter? Do you have a Business Static
>> IP
>> account from your ISP or is it Residential? I would suggest the
>> Smarthost
>> option as this point as your ISP mail server IP range are mostly
>> whitelisted
>> and would allow the mail to go through. Please clarify. Thanks.
>>
>> --
>> John Oliver, Jr
>> MCSE, MCT, CCNA
>> Exchange MVP 2010
>> Microsoft Certified Partner
>>
>>
>> "Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
>> news:9F47B39F-4C81-4F27-BE7D-8E3239418662(a)microsoft.com...
>> > Yes,
>> >
>> > I have an SPF record and reverse DNS Lookup that is configured
>> > properly.
>> > I've done a lot of those online "tests" and it always comes back ok.
>> >
>> > They don't give a reason. Once you fill out their form to get unblocked
>> > they
>> > send an auto generated email saying:
>> >
>> > "Our filters have determined that email from the IP you submitted was
>> > blocked because it sent email to the Comcast domain with patterns
>> > characteristics of spam. Mail servers are typically shared by many
>> > users
>> > so
>> > it may be the case that another party using your mail server has sent
>> > spam,
>> > even if you have not....."
>> >
>> > Any other ideas to see if our sever is actually sending spam without me
>> > knowing?
>> >
>> >
>> > "John Oliver, Jr. [MVP]" wrote:
>> >
>> >> Do you have an SPF Record? Do you have Reverse DNS Lookup Record?
>> >> Verify
>> >> this and if you are Blacklisted for any reason at www.dnsstuff.com.
>> >> Does
>> >> Comcast give a reason as why they are blocking you?
>> >>
>> >> --
>> >> John Oliver, Jr
>> >> MCSE, MCT, CCNA
>> >> Exchange MVP 2010
>> >> Microsoft Certified Partner
>> >>
>> >>
>> >> "Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
>> >> news:6EE5C287-B030-4704-AD0C-A314F9A640AC(a)microsoft.com...
>> >> > Hello all,
>> >> >
>> >> > Several months ago my company could not send emails to Comcast. I
>> >> > found
>> >> > out
>> >> > we were blocked. I filled out there request form to get unblocked
>> >> > and a
>> >> > couple of hours later they opened the pipe.
>> >> >
>> >> > Now, about once a month we keep getting blocked. Only from Comcast.
>> >> > I
>> >> > then
>> >> > fill out their form and they unblock us.
>> >> >
>> >> > I am running Exchange 2003 and using Symantec's Mail Security for
>> >> > Microsoft
>> >> > Exchange. This seems to do a pretty good job blocking incoming spam.
>> >> >
>> >> > Any idea why they continue to block us? What can I look at the help
>> >> > resolve
>> >> > this??
>> >> >
>> >> > Thanks,
>> >> > Jeff
>> >>
From: Ed Crowley [MVP] on 24 May 2010 16:59
You are hardly alone. I've had e-mail blocked by Comcast recipients and my
sending domain was one of AT&T's! You might want to contact Comcast's
postmaster, or contact the recipient you're trying to reach and have them
contact Comcast to complain that their mail is being blocked.
--
Ed Crowley MVP
"There are seldom good technological solutions to behavioral problems."
..

"Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
news:CEF6F1A4-251E-4FA9-8FDC-B5DD170D67E7(a)microsoft.com...
> Our Exchange server has a static IP that was given to us 7 years ago by
> our
> ISP.
> Our ISP manages our DNS (which I can modify any time)
> This is NOT Residential internet service.
>
> We are not doing a relay with our ISP - Everything is static.
>
> Comcast is the only problem we're having.
>
> One thing that may be an issue, which I would like your opinion - Our
> firm's
> signature file in Outlook consists of 3 attachments (graphics files) We
> are
> also sending email as HTML and not plain text.
>
> Thanks for your help so far.
> Jeff
>
>
> "John Oliver, Jr. [MVP]" wrote:
>
>> Jeff,
>>
>> Can you please give some info on your ISP setup? Are you using them as a
>> Smarthost or anyone else for that matter? Do you have a Business Static
>> IP
>> account from your ISP or is it Residential? I would suggest the
>> Smarthost
>> option as this point as your ISP mail server IP range are mostly
>> whitelisted
>> and would allow the mail to go through. Please clarify. Thanks.
>>
>> --
>> John Oliver, Jr
>> MCSE, MCT, CCNA
>> Exchange MVP 2010
>> Microsoft Certified Partner
>>
>>
>> "Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
>> news:9F47B39F-4C81-4F27-BE7D-8E3239418662(a)microsoft.com...
>> > Yes,
>> >
>> > I have an SPF record and reverse DNS Lookup that is configured
>> > properly.
>> > I've done a lot of those online "tests" and it always comes back ok.
>> >
>> > They don't give a reason. Once you fill out their form to get unblocked
>> > they
>> > send an auto generated email saying:
>> >
>> > "Our filters have determined that email from the IP you submitted was
>> > blocked because it sent email to the Comcast domain with patterns
>> > characteristics of spam. Mail servers are typically shared by many
>> > users
>> > so
>> > it may be the case that another party using your mail server has sent
>> > spam,
>> > even if you have not....."
>> >
>> > Any other ideas to see if our sever is actually sending spam without me
>> > knowing?
>> >
>> >
>> > "John Oliver, Jr. [MVP]" wrote:
>> >
>> >> Do you have an SPF Record? Do you have Reverse DNS Lookup Record?
>> >> Verify
>> >> this and if you are Blacklisted for any reason at www.dnsstuff.com.
>> >> Does
>> >> Comcast give a reason as why they are blocking you?
>> >>
>> >> --
>> >> John Oliver, Jr
>> >> MCSE, MCT, CCNA
>> >> Exchange MVP 2010
>> >> Microsoft Certified Partner
>> >>
>> >>
>> >> "Jeff" <Jeff(a)discussions.microsoft.com> wrote in message
>> >> news:6EE5C287-B030-4704-AD0C-A314F9A640AC(a)microsoft.com...
>> >> > Hello all,
>> >> >
>> >> > Several months ago my company could not send emails to Comcast. I
>> >> > found
>> >> > out
>> >> > we were blocked. I filled out there request form to get unblocked
>> >> > and a
>> >> > couple of hours later they opened the pipe.
>> >> >
>> >> > Now, about once a month we keep getting blocked. Only from Comcast.
>> >> > I
>> >> > then
>> >> > fill out their form and they unblock us.
>> >> >
>> >> > I am running Exchange 2003 and using Symantec's Mail Security for
>> >> > Microsoft
>> >> > Exchange. This seems to do a pretty good job blocking incoming spam.
>> >> >
>> >> > Any idea why they continue to block us? What can I look at the help
>> >> > resolve
>> >> > this??
>> >> >
>> >> > Thanks,
>> >> > Jeff
>> >>

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