I get for try to block the MSN Messenger service:
Block port tcp 1863 and udp 1863.
Block the access for http and https to some domains:
appdirectory.messenger.msn.com
c.msn.com
config.messenger.msn.com
contacts.msn.com
crl.microsoft.com
edge.messenger.live.com
g.msn.com
gateway.messenger.hotmail.com
images.messenger.msn.com
messenger.hotmail.com
messenger.msn.com
ows.messenger.msn.com
rad.msn.com
relay.messenger
relay.voice.messenger.msn.com
rsi.hotmail.com
spaces.live.com
sqm.microsoft.com
storage.msn.com
sup.live.com
vp.sip.messenger.msn.com
And the last