Entourage 2008 Not Connected - HTTP/1.1 503 Service Unavailable

You may get a case where everyone that's using Entourage is not able to connect to the Exchange Client Acccess servers.

Troubleshooting

You might try and access whatever server URL Entourage will try and access via a web browser, and you will get the following error:

(i.e.) URL: https://owaurl/exchange/email-address

Error: HTTP/1.1 503 Service Unavailable

You might verify the Client Access (CAS) server logs and find something similar to the below:

2010-01-01 01:01:01 111.11.1113.11 PROPFIND /exchange/USERNAME/ - 80 DOMAIN\USERNAME 10.100.10.100 Entourage/12.20.0+(Intel+Mac+OS+X+10.5.7) 503 0 0 234

Solution:

This is most likely to be caused by WebDav being prohibited (CAS) or IIS not working correctly on the mailbox server.

Applies to: Windows Server 2003 / Exchange Server 2007