If you want to use the Microsoft Online Services Single Sign in tool. Check the C:\Program Files\Microsoft Online Services\Sign In\SignIn.exe.config file first!
The tool wouldn't want to authenticate me although my username & password were correct.
Why check the config file?
First of all you need to know where exactly your online service is located.
if you use emea (Europe, the Middle East and Africa) like I do, check the C:\Program Files\Microsoft Online Services\Sign In\SignIn.exe.config. At the bottom of this file there is an endpoint element.
make sure this elements address is referring to the correct url
EMEA users –> https://signinservice.emea.microsoftonline.com/ssoservice and not https://signinservice.microsoftonline.com/ssoservice like in my case.
this small change enabled me to use this tool without any other problem.
Do not try to connect your outlook with the BPOS Exchange server. Outlook supports only 1 exchange account at a time so the other one will be removed. Make sure you export a backup (*.PST) first!