http://blogs.msdn.com/dgoldman/archive/2007/08/10/installing-exchange-2007-in-to-a-mixed-organization-will-create-a-valid-pdn-entry-and-break-oab-generation.aspxNew PDN's are really bad and will they will break the OAB Generation process. For most of the fixes you can follow my other blog found here: [ http://blogs.msdn.com/dgoldman/archive/2005/11/18/OAB-PDN-Changes-and-Exchange-Site-Consolidations.aspx ] whichen-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/dgoldman/archive/2007/08/10/installing-exchange-2007-in-to-a-mixed-organization-will-create-a-valid-pdn-entry-and-break-oab-generation.aspx#4416150Thu, 16 Aug 2007 17:37:09 GMT91d46819-8472-40ad-a661-2c78acb4018c:4416150Ben<p>Hi, have read all you comments re OAB generation with Exchange 2007. All good. &nbsp;However, with your trouble shooting, you state check the autodiscover configuration and the autodiscover.xml for the OAB URL. But no comment as what to look for when it does not appear? The OAB URL that is... everything else works fine, and autodiscover is fine, and the internal/external URLS are set on the OABVirtualdirectory and no errors reported by anything anywhere, except not able to download OAB, due to missing URL... which indeed appears to be missing.... </p>http://blogs.msdn.com/dgoldman/archive/2007/08/10/installing-exchange-2007-in-to-a-mixed-organization-will-create-a-valid-pdn-entry-and-break-oab-generation.aspx#4431465Fri, 17 Aug 2007 18:46:58 GMT91d46819-8472-40ad-a661-2c78acb4018c:4431465subject: exchange<p>Making Sense of the Wireless World Info Center Configuring Microsoft Exchange Direct Push technology</p>