I have recently implemented a new Exchange 2003 SP2 backend server, which is accessed for OWA via a 2003 SP1 front-end in a DMZ. If I move the mailbox tothe new backend server and try to access it remotely via OWA it rejects the username/password. If I connect locally from the DMZ serverto its url \\srv1\exchange it works ok. If I move the mailbox to an existing Exchange server on the same site it is ok via the same front end. It seems the problem is specific to the new server, but OWA works ok directly on the server and from the DMZ box usin it local url so I dont thing the problem is HTTP connectivity. I can also ping the backend from the DMZ and all three other backends are working ok. It doesn't work if I enter the front-end as the url which is basically them same as accessing from the web. Ports from DMZ are 80, 691, 389, 3268, 88, 53 Note all existing infrasture if ok and it just affect the new Exchange 2003 backend server when accessed via the OWA server in the DMZ. Not sure how to troubleshoot this. Any help much appreciated.

Check the Authentication method on the new backend serverhttp://www.microsoft.com/technet/prodtechnol/exchange/Guides/E2k3FrontBack/9713985e-8847-4104-be02-6d00af9243e1.mspx?mfr=true

Hi, For me should also apply the SP2 to the front-end. This is whta Microsoft recommend in general. If you check the exchange director, there is a folder called 'Exchweb' with subdirectories. Each of this subdirectory equals a SP or Hotfix. You must have the highest one of the BackEnd alo on teh FrontEnd

Agree with the other guys but maybe the below will explain ... I had the same problem and was banging my head against a wall about this. Got the service packs to the same level and all was resolved. Only afterwards that I found the reason why this happens in the 'Exchange Front-End\Back-End Topology Guide'. There's an extract below that I found relevant to this problem. Hope this helps. Thanks, Mark If Outlook Web Access is deployed in your organization, you should upgrade every front-end server in the organization before you upgrade any back-end servers. This is because how Outlook Web Access is built. At a high level, Outlook Web Access data comprises two parts: templates and controls. Templates are items such as forms (e-mail messages, calendar items, and other forms). Controls are files such as DHTML behaviors, JScript files, style sheets, and images that are stored in the /exchweb virtual directory in IIS. When a user accesses Outlook Web Access through the front-end server, the templates actually come from the back-end server, and the controls come from the front-end server. The templates come from the back-end for performance reasons. The controls come from the front-end server because there is no mechanism to proxy a request for data that is not in the Exchange store from a front-end server to a back-end server. This is not a problem as long as the front-end and back-end servers run the same version and service pack of Exchange. A problem arises when the servers run different versions of service packs. If a template on a back-end server references a control on a front-end server, and the front-end server is running an earlier service pack, the control the back-end server is referencing might not exist. As a result, Outlook Web Access does not work for users whose mailboxes are on the upgraded back-end server.The reverse situation does not have the same problem. If you upgrade a front-end server first, users see templates from the back-end server. These templates reference the earlier versions of the controls, which still exist on the front-end server, because the files are versioned and not removed in an upgrade. To address this issue, it is recommended that you upgrade all front-end servers before upgrading any back-end servers.