Postfix SMTP server: errors from something.net[ip address]

2 msg	Postfix SASL Help
6 msg	Slowing down postfix
2 msg	need help deciphering a line

Postfix SMTP server: errors from something.net[...
\ Guy Story KC5GOI (22 Jan 2008)
. \ (Wietse Venema) (22 Jan 2008)
. . \ Guy Story KC5GOI (22 Jan 2008)
. . . \ (Wietse Venema) (22 Jan 2008)

4 msg	2.5.0-RC and 2.6 should recognize FreeBSD 8
9 msg	Postfix not following my access file.
3 msg	postfix logs delay, delays, dsn
3 msg	Best way to shutdown postfix prior to servicing...
1 msg	the bounce process hangs a mail (?)
3 msg	messages destined for content_filter stuck in d...
2 msg	Domain in username
5 msg	missing authentication on recipient
5 msg	postfixadmin
5 msg	check_policy_service before reject_rbl_client
9 msg	MXBackup via LDAP
5 msg	header and body check exemptions
5 msg	Relay recipient maps and relocated users
4 msg	mail forwarding loop :: SPAM
3 msg	transport_maps how to match mx's
2 msg	Where/when to insert a missing Message-ID

Subject:	Postfix SMTP server: errors from something.net[ip address]
Group:	Postfix-users
From:	Guy Story KC5GOI
Date:	22 Jan 2008

Can someone help me make sure I am reading this correctly. It is
occurring for only one sender. The addresses it is sending to are legit
and actively working accounts. I have hidden the domains and the user
account.

Transcript of session follows.

Out: 220 mail.myserver.com ESMTP Postfix (Ubuntu)
In: EHLO hidden_domain.net
Out: 250-mail.myserver.com
Out: 250-PIPELINING
Out: 250-SIZE 20480000
Out: 250-VRFY
Out: 250-ETRN
Out: 250-STARTTLS
Out: 250-ENHANCEDSTATUSCODES
Out: 250-8BITMIME
Out: 250 DSN
In: MAIL FROM:<root> SIZE=35596
Out: 250 2.1.0 Ok
In: RCPT TO:<legit_account>
Out: 451 4.3.5 Server configuration error
In: DATA
Out: 554 5.5.1 Error: no valid recipients
In: RSET
Out: 250 2.0.0 Ok
In: QUIT
Out: 221 2.0.0 Bye

I understand the first IN as the connecting server saying hello, the
next 9 OUTS are information being sent to the connecting server. I know
the SIZE parameter is rather large, long story. The next IN has the
sender address which happens to be a regularly sent newsletter. The OUT
after the In: RCPT TO: has me confused since it only happens to two of
my accounts and no one else. I even tested it as a sanity check. For
example, I can send to that address from my gmail account and there are
not problems reported in the logs. It is almost like the recipient in
the IN: RCPT field is buggered somehow. This is hitting 2 of my user
accounts. The log file has the following error:

NOQUEUE: reject: RCPT from hidden_domain.net[hidden ip]: 451 4.3.5
Server configuration error; from=<root>
to=<legit_user> proto=ESMTP helo=<hidden_domain.net>

I have read over http://www.postfix.org/SMTPD_ACCESS_README.html in the
section that talks about Restrictions that apply to all SMTP mail. In
the paragraph about MAIL FROM or RCPT TO, it indicates that a
misconfigured sending server could cause issues. I do not have
strict_rfc821_envelopes in my main.cf. Per the page that is turned off
by default. I get the impression that the converstation at the RCPT
phase is broken because of what the sending server is sending.

Still learning Postfix so I appreciate the patience and help. Do I need
to send a copy of my main.cf?

Guy

--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
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begin:vcard
fn:Guy Story
n:Story;Guy
org:Texas Hematology Oncology/PCCC;IT
adr:;;4352 North Josey Lane;Carrollton;Tx;75010;USA
email;internet:gstory
title:MIS Manager
tel;work:214.483.5900
tel;fax:972.394.0680
x-mozilla-html:FALSE
url:http://www.pccctx.com
version:2.1
end:vcard