We have made a fresh installation of Small Business server 2011 including Ms Exchange 2010.
I've run the guides in the SBS Console and also made some small changes in Exchange manager.
So things are pretty "fresh" and https://webmail.domain.com/owa works like a charm.
I have followed the instruction exactly here: http://briandesmond.com/blog/redirecting-owa-urls-in-exchange-2010/
to redirect requests to http://webmail.domain.com to https://webmail.domain.com/owa
http://webmail.domain.com now takes me to the login screen (form based). Perfect. But after entering the credentials I get a HTTP 400-error and the address bar shows:
I press F5 (reload), the page is reloaded and I'm in, and from here everything seems to work.
So, pointing the browser to the main domain name without /owa (and getting redirected to (owa) gives the error described above, any ideas about that?