Re: [exim] Problem sending Mail to comcast

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Author: Tom Fischer
Date:  
To: exim-users
Subject: Re: [exim] Problem sending Mail to comcast
Jeremy Harris wrote:

> Tom Fischer wrote:
>
>>     i have much trouble sending to comcast Mailservers. The comcast 
>> Servers returns "450 [TEMPFAIL] comcast.net requires valid sender domain".


> So, what domain does the envelope-from have on a typical mail
> that gets rejected? Does that domain exist, have proper rDNS
> and matching forward DNS?


It is artedona.de. The Domain exist. They relay about our Mail-Server
which is located at 82.135.22.122. IMO DNS is correct.

> Sometimes the mail goes thru after a few hours but mostly not.
>
> Is your DNS provider unreliable?


No, the Nameserver are our own and monitoring does not notifiy a failure.

>     What i can see with ngrep

>
> ngrep of what?


Tranmission from our Relay to comcast Server.

>> is that my exim must wait a long time for Return Messages and then
>> send line to the comcast servers like this
>
> "From:<xyz@xxxxxxxxxxxxxxxxxx> To:<xyz@xxxxxxxxxxx> ..."
>
> Please, don't obfuscate. It makes it hard for us to help you.
> Post a complete log segment of a failing transaction.


T 82.135.22.122:33469 -> 204.127.198.26:25 [AP]
MAIL FROM:<xyz@???> SIZE=29546..RCPT
TO:<xyz@???>..DATA..

And this is abnormal. Btw Comcast is the only one we have Problems with.

>> and does not wait for return code, so comacst servers saw the
>> To-Header not correctly.
>
> Unlikely to be the headers (the 822 addresses). More likely
> to be the envelope (the 821 addresses, specifically the From).


I think i was unclear, sorry but english is not my native language. What
i mean is that exim transmits the Mail FROM:, SIZE, RCPT TO and DATA in
one piece without waiting for the return code from comcast Server and so
it sees the From (not the to, my fault) like this <service@???>
SIZE=29546..RCPT and gives then back (correctly) that this is not a
valid sender Domain. I think the Problem here is that my exim waits near
to Time-Out from TCP Protocol because comcast Server doesn't answer.

Here is the log from one mail which could be send later:

Feb 7 12:02:39 Lord_Nikon exim[7728]: 2006-02-07 12:02:39
1F6QcJ-00020e-HK <= xyz@??? H=82.135.59.20.ebuz-kunden.de
(STARGATE2.match.intra) [82.135.59.20] P=esmtp S=27588
id=C19787E572D11243887A6C30AEA210E9C0210E@???

Feb 7 12:08:50 Lord_Nikon exim[7730]: 2006-02-07 12:08:50
1F6QcJ-00020e-HK SMTP error from remote mailer after RCPT
TO:<xyz@???>: host gateway-s.comcast.net [63.240.76.26]: 450
[TEMPFAIL] comcast.net requires valid sender domain

Feb 7 15:36:21 Lord_Nikon exim[8358]: 2006-02-07 15:36:21
1F6QcJ-00020e-HK == xyz@??? R=dnslookup T=remote_smtp defer
(-44): SMTP error from remote mailer after RCPT TO:<xyz@???>:
host gateway-r.comcast.net [216.148.227.126]: 450 [TEMPFAIL] comcast.net
requires valid sender domain

Feb 7 15:55:55 Lord_Nikon exim[8443]: 2006-02-07 15:55:55
1F6QcJ-00020e-HK => xyz@??? R=dnslookup T=remote_smtp
H=gateway-s.comcast.net [204.127.202.26]


>> I think that the problem is on comcast Side but how to explain my
>> customers.
>
> I suspect not.
>
> - Jeremy


Thank you for your time

Regards

Tom

P.S. Sorry for breaking threading :-(