After a reboot of the SBS 2008 server, this startet to happen at the clients. They log on to the domain, open Outlook and are asked for credentials. They have to enter this several times before it's accepted.
OWA is working normally with SSL certificate. I also notice that when I set up an email account in Outlook 2007 it's also asking for username/password when it searches for the server. This has been working fine earlier. Is this something to do with the SSL certificate? I see that when I'm asked for credentials, the mail.domain.com is displayed as servername, not the FQDN for the server.
Any suggestions? Thanks a lot!