Checking for updates.
It will only ever connect to
http://www.hotmailstuff.com/update a maximum of once per day, and only download about 25 bytes max, and will not send any data about you, your program or anything else.
On some systems a connection may be made to
http://www.hotmailstuff.com/download/* to download updates and required files, but this will happen only for new versions or at installation.
BetterMSN is 100% open source, so there is no need to take my word for it, have a look at the source code:
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*c...nt-type=text/plain and look for the function CheckUpdate.