[Mailman-Users] Tangential Delivery Question

Mark Sapiro msapiro at value.net
Wed Nov 9 06:59:30 CET 2005

David Hwang wrote:

>I know this is probably tangential to the purpose of the list, but
>people here have been very friendly and helpful in my quest to get 
>mailman up and running on my Trustix system.
>I was following the mail delivery logs and came across some odd errors 
>that I'm hoping someone can help me decipher and  ultimately find a fix.
>Or if someone has a suggestion where a better place to ask might be, I'd 
>appreciate that as well.

You're right. This is off topic for this list, but ...

>This is what I'm seeing:
>Nov  8 01:10:04 m5 postfix/smtp[1035]: 9CD0117F3B: 
>to=<jblumberg at comcast.net>, relay=gateway-s.comcast.net[], d
>elay=58387, status=deferred (host gateway-s.comcast.net[] 
>said: 450 [TEMPFAIL] comcast.net requires valid sende
>r domain (in reply to RCPT TO command))
>Nov  8 01:10:04 m5 postfix/smtp[1040]: 9608F17F45: 
>to=<hotyakker at comcast.net>, relay=gateway-r.comcast.net[],
>delay=13841, status=deferred (host 
>gateway-r.comcast.net[] said: 450 [TEMPFAIL] comcast.net 
>requires valid s
>ender domain (in reply to RCPT TO command))
>Nov  8 01:10:05 m5 postfix/smtp[1043]: 5B71317F43: 
>to=<jhwang at comcast.net>, relay=gateway-r.comcast.net[], de
>lay=5035, status=deferred (host gateway-r.comcast.net[] 
>said: 450 [TEMPFAIL] comcast.net requires valid sende
>r domain (in reply to RCPT TO command))
>Nov  8 01:10:07 m5 postfix/smtp[1030]: 6F0C917F47: 
>to=<jhwang at comcast.net>, relay=gateway-r.comcast.net[], d
>elay=4409, status=deferred (host gateway-r.comcast.net[] 
>said: 450 [TEMPFAIL] comcast.net requires valid sen
>der domain (in reply to RCPT TO command))
>What does "comcast.net requires valid sender domain (in reply to RCPT TO 
>command))" mean?

I've seen this before and here's what's happening. Your postfix is
trying to deliver a message to these users in the comcast.net domain.
It establishes an SMTP connection with an SMTP server at
gateway-r.comcast.net. It starts by identifying itself with a HELO or
EHLO command, e.g.

EHLO your_domain

or similar and receives an afirmative reply

It then says

MAIL FROM <sender_address>

to initiate sending mail. This specifies the sender of the envelope. It
gets an afirmative reply and then sends

RCPT TO <jblumberg at comcast.net>

for example, and receives

450 [TEMPFAIL] comcast.net requires valid sender domain

in reply. This means gateway-r.comcast.net didn't like the domain part
of <sender_address>. Maybe it's missing. Maybe it doesn't have a DNS
entry. Normally, it is set by the originator of the mail - Mailman if
it is delivery of a list post, your MUA if it is a mail you composed
and sent.

>I assume that I've got something wrong in my configuration (Postfix, 
>Spamassassin, Amavisd, Mailman) or in my DNS, but where should I start 

It could be a Mailman issue if these are list messages. Mailman sets
the envelope sender for a list post to listname-bounces at host_name or
if VERP'd listname-bounces+user=user_domain at host_name. In any case,
the sender domain is the host_name attribute of the list which is
visible on the General Options page.

For more info, see for example

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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