I have searched around but found no results, I guess everyone's case is going to be different...
I have tested this on AOL, Yahoo, Hotmail, Gmail, Gmail school account, etc...

All go through just fine except Gmail account, just regular mail is being marked as spam even though my SPF = pass;
Received-SPF: pass (google.com: domain of xxx)

PHP Code:
Delivered-Toxxx@gmail.com
Received
by 10.68.27.72 with SMTP id r8csp396378pbg;
        
Fri13 Jul 2012 07:26:31 -0700 (PDT)
Receivedby 10.42.145.7 with SMTP id d7mr876132icv.45.1342189590597;
        
Fri13 Jul 2012 07:26:30 -0700 (PDT)
Return-
Path: <user@xxx.org>
Receivedfrom xxx.org (rrcs-24-172-204-102.central.biz.rr.com. [xxx])
        
by mx.google.com with ESMTP id a5si2834150igd.60.2012.07.13.07.26.29;
        
Fri13 Jul 2012 07:26:30 -0700 (PDT)
Received-SPFpass (google.comdomain of user@xxx.org designates xxx as permitted senderclient-ip=xxx;
Authentication-Resultsmx.google.comspf=pass (google.comdomain of user@xxx.org designates xxx as permitted sendersmtp.mail=user@xxx.org
Received
from localhost (localhost.localdomain [127.0.0.1])
    
by xxx.org (Postfixwith ESMTP id 552651F20B1
    
for <xxx@gmail.com>; Fri13 Jul 2012 10:26:29 -0400 (EDT)
X-Virus-Scannedamavisd-new at xxx.org
Received
from xxx.org ([127.0.0.1])
    
by localhost (xxx.org [127.0.0.1]) (amavisd-new, port 10024)
    
with ESMTP id qdVwn0qPEeUU for <xxx@gmail.com>;
    
Fri13 Jul 2012 10:26:25 -0400 (EDT)
Receivedfrom xxx.org (xxx.org [10.10.10.10])
    
by xxx.org (Postfixwith ESMTP id 37F691F20B0
    
for <xxx@gmail.com>; Fri13 Jul 2012 10:26:25 -0400 (EDT)
DateFri13 Jul 2012 10:26:25 -0400 (EDT)
Fromxxx <user@xxx.org>
Toxxx@gmail.com
Subject
FwdREBAR DRIVERS
Message
-ID: <024d456e-5f3f-4f00-b2f7-c5619ef0451e@xxx.org>
In-Reply-To: <973720B011431D46B9798539D7AE0D190188839F@wosnpntcmx013.DS.WOLSELEY.COM>
Content-Typemultipart/alternative;
 
boundary="=_9878d2e1-095f-4167-87d1-35d722c845d7"
MIME-Version1.0
X
-Originating-IP: [xxx]
X-MailerZimbra 7.1.3_GA_3346 (ZimbraWebClient FF3.0 (Win)/7.1.3_GA_3346