[Fwd: Postfix SMTP server: errors from avalanche.netmar.com[198.69.224.177]]

Can someone tell me if I'm blocking spam here of if I'm somehow blocking
some of the emails from this list?

I'm definitely getting email, but I keep getting these messages popping
up on my servers. Does anyone know why?

-------- Original Message --------
Return-Path: <double-bounce(at)cling(dot)tacocat(dot)net>
X-Original-To: postmaster
Delivered-To: postmaster(at)tacocat(dot)net
Received: by cling.tacocat.net (Postfix) id 6D9B34C07A; Wed, 16 Jun 2004
19:19:33 -0400 (EDT)
Date: Wed, 16 Jun 2004 19:19:33 -0400 (EDT)
From: MAILER-DAEMON(at)cling(dot)tacocat(dot)net (Mail Delivery System)
To: postmaster(at)tacocat(dot)net (Postmaster)
Subject: Postfix SMTP server: errors from
avalanche.netmar.com[198.69.224.177]
Message-Id: <20040616231933(dot)6D9B34C07A(at)cling(dot)tacocat(dot)net>

Transcript of session follows.

Out: 220 cling.tacocat.net ESMTP Postfix (Debian/GNU)
In: EHLO avalanche.technically-sound.com
Out: 250-cling.tacocat.net
Out: 250-PIPELINING
Out: 250-SIZE 10240000
Out: 250-VRFY
Out: 250-ETRN
Out: 250 8BITMIME
In: MAIL FROM:<pgsql-general-owner+M61963(at)postgresql(dot)org> SIZE=3112
Out: 250 Ok
In: RCPT TO:<tallison(at)tacocat(dot)net>
Out: 450 <pgsql-general-owner+M61963(at)postgresql(dot)org>: Sender address
rejected:
unverified address: Address verification in progress
In: DATA
Out: 554 Error: no valid recipients
In: RSET
Out: 250 Ok
In: QUIT
Out: 221 Bye