spam spoofing email address?

[Galactic Zero]

I'm getting alot of spam that is not being flagged. I know it is taking advantage of me by spoofing my email address:

Here is the header:

Return-Path: <>
Delivered-To: 1-info@galacticzero.net (is the exploit I think)
X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on gz.galacticzero.net
X-Spam-Level:
X-Spam-Status: No, score=0.7 required=7.0 tests=FUZZY_AMBIEN,
MAILTO_TO_SPAM_ADDR autolearn=no version=3.1.0
Received: (qmail 27643 invoked by uid 2520); 1 Dec 2005 04:41:51 -0000
Received: from 64.12.138.17 by gz.galacticzero.net (envelope-from <>, uid 2020) with qmail-scanner-1.25st
(clamdscan: 0.87.1/1198. perlscan: 1.25st.
Clear:RC:0(64.12.138.17):.
Processed in 0.147234 secs); 01 Dec 2005 04:41:51 -0000
Received: from omr-m05.mx.aol.com (64.12.138.17)
by www.galacticzero.net with SMTP; 30 Nov 2005 22:41:51 -0600
Received: from rly-nc02.mx.aol.com (rly-nc02.mail.aol.com [172.18.151.199]) by omr-m05.mx.aol.com (v107.10) with ESMTP id RELAYIN8-9438e7ee4150; Wed, 30 Nov 2005 23:41:08 -0400
Received: from localhost (localhost)
by rly-nc02.mx.aol.com (8.8.8/8.8.8/AOL-5.0.0)
with internal id XAG18253;
Wed, 30 Nov 2005 23:41:08 -0500 (EST)
Date: Wed, 30 Nov 2005 23:41:08 -0500 (EST)
From: Mail Delivery Subsystem <MAILER-DAEMON@aol.com>
Message-Id: <200512010441.XAG18253@rly-nc02.mx.aol.com>
To: <info@galacticzero.net>
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
boundary="XAG18253.1133412068/rly-nc02.mx.aol.com"
Subject: Returned mail: User unknown
Auto-Submitted: auto-generated (failure)
X-AOL-IP: 172.18.151.199


How do I close this and where to I enable auto learn for the server/user thanks?

Thanks