I've downloaded Scalix 10, and I must say I am VERY impressed with it.
However I did notice something strange when receiving email from mailing lists. Previously the information in the "From:" header was populated into the "From" coloumn in Outlook. However, in Scalix 10 the information in the "Sender:" header is populated into this coloumn.
The problem is that certain mailing list managers (specifically Mailman and Yahoo! Groups) put the list address or list manager address or even the list bouncing address. If you then do a "Reply" the address that gets picked up is an administrative address, instead of the orignal sender.
If the "Sender:" header is missing, the "From:" header is used correctly. SWA displays the correct address from the "From:" field.