RE: smtp problem: Status: 4.4.7 Unable to contact host
From: Tom Linden (tom_at_kednos.com)
Date: 10/08/03
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Date: Wed, 8 Oct 2003 08:36:27 -0700
I gave up on tcpip5.1 because of its primitive spam filtering
and switched to MX5.3 and I am glad I did.
>-----Original Message-----
>From: sol gongola [mailto:sol@adldata.com]
>Sent: Wednesday, October 08, 2003 8:29 AM
>To: Info-VAX@Mvb.Saic.Com
>Subject: Re: smtp problem: Status: 4.4.7 Unable to contact host
>
>
>John Johnstone wrote:
>>
>> sol gongola wrote:
>> >
>> > Compaq TCP/IP Services for OpenVMS Alpha Version V5.1 - ECO 3
>> > on a AlphaServer 2100 4/275 running OpenVMS V7.2-1
>> >
>> > So far 3 people have been 'reproducibly' unable to email us. 2
>are coming
>> > from comcast, 1 from worldnet.att.net. No one else from these sites has
>> > been trying to send us email so i don't know for sure if the sender is
>> > the problem . The bounced messages all have the same status message:
>> >
>> > Final-Recipient: rfc822; SOL@ADLDATA.COM
>> > Action: failed
>> > Status: 4.4.7 Unable to contact host for 1 days,
>> > Diagnostic-Code: smtp; Persistent Transient Failure:
>Delivery time expired
>> > Last-Attempt-Date: 1 Oct 2003 21:02:13 +0000
>> >
>> > I am using smtp.config but I don't think anything I can put into
>> > smtp.config could have caused this.
>> >
>> > We are not having any problems receiving messages from others.
>> > Does anyone know what could be causing this.
>> >
>> > thank you
>> > sol gongola
>> > adl data systems inc
>> > dobbs ferry, ny
>>
>> I just tried a telnet to port 25 of mail.adldata.com and there was a
>> pause of about one minute before I saw the 220 announcement from your
>> mail server. That would correspond to the timeout for the IP address to
>> name lookup that your server would be doing. I was coming from an
>> address that should resolve back to a name but after my HELO test, your
>> machine's 250 response had "Hello unknown.hostname" in it. It looks
>> like your system's DNS resolver isn't working. If all of your recent
>> incoming mail has "unknown.hostname" in the received headers, then I
>> think that would confirm it.
>>
>> If your Comcast and ATT mail is coming from their servers and not
>> directly from one of their users, it looks like they've got poorly
>> configured servers that have a initial timeout of less than one minute.
>> At each attempt, their systems are probably giving up before your system
>> puts out its 220 announcement. Any system that has a timeout of more
>> than a minute will still get through.
>
>I see that a few of the received emails have unknown.hostname.
>Some of them I can
>resolve with nslookup (or dig) from the same Alpha as the smtp server.
>The rest couldn't be resolved by any 'online' nslookup sites so
>the unresolved
>must be 'valid'.
>
>The operator.log is not showing any messages other than the
>expected RBL and other
>smtp.config related messages (I get at least 1 RBL related block a minute)
>
>I was thinking that the RBL lookups and Bad client list in
>smtp.config might
>be slowing things down enough to be a problem but i am not sure if
>that would
>cause the unknown host situation.
>
>Sol Gongola
>ADL Data Systems Inc.
>
>---
>Incoming mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.518 / Virus Database: 316 - Release Date: 9/11/2003
>
--- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.518 / Virus Database: 316 - Release Date: 9/11/2003
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