OK, so you’ve just installed Exchange 2013. Everything is working fine untill you find that windows XP clients with both outlook 2007 & 2010 are prompting you for passwords.
Both versions of outlook are fully supported as is windows XP & windows 7 clients are working fine so what gives?
The answer as it turns out is quite simple. The Exchange Certificate common name must match the exchange server name. Even if the Exchange server name is listed in the SAN (subject alternative names) windows XP will prompt for credentials. SO you can either make sure that when you create the SAN certificate that the Exchange name is the common name or run the following command:
Set-OutlookProvider EXPR -CertPrincipalName:”msstd:mail.company.com”
After running the command issue “iisreset”.
Hope this helps anyone with the same issue.
Take note here: If you have windows xp clients that are connecting both internally and externally using Outlook anywhere your going to have to set up split DNS and use the same namespace for both internal & external clients or set up a Proxy (Microsoft TMG or UAG) and issue seperate certificates with seperate common names.