Re: [exim] Gmail and Google blocking inbound port 25?

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Author: Mike Lyon
Date:  
To: W B Hacker
CC: exim users
Subject: Re: [exim] Gmail and Google blocking inbound port 25?
Well, I have the forward and reverse IPs matching. Don't have any MX
records for that specific domain set-up because I don't have any inbound
mail setup for that domain (nor do I want it).

It's an IP block that was allocated to us from ATT on a business circuit. I
checked the IP addresses on MX toolbox and they come up clean

Would they actually refuse the connection if there were no MX records for
that domain?

Thanks,
Mike


On Fri, Jun 1, 2012 at 12:53 PM, W B Hacker <wbh@???> wrote:

> Mike Lyon wrote:
>
>> Howdy,
>>
>> I know this isn't an exim related question but it's affecting the ability
>> for my exim install to deliver email... Anyways, It appears when my exim
>> install tries to deliver email to Google or Yahoo, both of them refuse the
>> port 25 connection from my host. I went to another server I have in a
>> different subnet and was able to telnet to port 25 at both Google and
>> Yahoo. So it appears they are blocking this one subnet I have from
>> connecting to them.
>>
>> How does one resolve this issue?
>>
>> Thank You,
>> Mike
>>
>
> 'Stock' answer is to investigate the subnet with a 'whois' and see how it
> is allocated. If 'AP' - as most 'residential' connectivity pools, and
> all-too many so-called 'business' broadband are, then check also RBL's such
> as SORBS and the like that target dynamic-IP block ranges.
>
> These are sometimes 'discovered' and other times voluntarily listed by ISP
> who have a ToS that prohibits running MTA etc - then operate an MTA on a
> different block for use of their connectivity pool subscribers.
>
> Hard to get around that. Potentially harder yet if it is a Google-specific
> LBL. Several majors, such as the former 'Baby bell' in the US, are doing
> that now on perfectly good IP blocks, sometimes purely on a basis of GeoIp
> or host country of the block holder.
>
> I'm presuming, of course, that with your experience level, you already
> have a valid non-generic, FQDN-relevant, PTR RR and matching MX DNS
> entries. Absent that, a BL needn't be checked, as a vanilla reverse lookup
> fails.
>
> Bill
> --
> 韓家標
>
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--
Mike Lyon
408-621-4826
mike.lyon@???

http://www.linkedin.com/in/mlyon