We send daily mass emails to our customers (~30,000+ emails per day). We have problems with Hotmail users receiving our emails. Sometimes the email goes to the Junk folder, but often it will got to their inbox, but the content is blocked so the user sees a message saying "This email was blocked and may be dangerous". If an email is sent to GMAIL it is usually not blocked, but it does show up as from "Uknown" instead of the company.
Please be advised I've done the following: 1. No RBLs Checked on -> http://multirbl.valli.org/ 2. We do have SPF records published 3. We do have reverse DNS setup 4. Our company even signed up for the Junk Mail Reports Program at Hotmail
Here is a sample header, I've noticed the X-SID-Result and the X-AUTH-Result both FAIL every time at Hotmail:
X-Message-Delivery: Vj0xLjE7dXM9MDtsPTA7YT0wO0Q9MTtTQ0w9MQ== X-Message-Status: n:0 X-SID-Result: Fail X-AUTH-Result: FAIL X-Message-Info: JGTYoYF78jFqAaC29fBlDlD/ZI36+S6WoFmkQN10UxWFe1xLHhP+rDthGRZM87uHYM926hUBS+s0q46Yx9y6jdurhN6fx0bK Received: from privatecompany.com ([WanIPAddress]) by col0-mc3-f30.Col0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 5 May 2010 08:41:27 -0700 X-AuditID: ac10fe93-000013bc00000534-46-4be191a1618e Received: from INTERNAL-Email-SERVER([InternalIPAddress]) by privatecompany.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 5 May 2010 11:41:21 -0400 From: Private Company, Inc.<EmployeeUsername@privatecompany.com> To: PrivateClient@hotmail.com Message-Id: <firstname.lastname@example.org> Subject: Date: Wed, 5 May 2010 11:42:46 -0400 MIME-Version: 1.0 Reply-To: EmployeeUsername@privatecompany.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: AAAAAA== Return-Path: email@example.com X-OriginalArrivalTime: 05 May 2010 15:41:27.0837 (UTC) FILETIME=[6D06E4D0:01CAEC69]