For Windows Live Messenger with Messenger Plus! Live:
1) Turn off the notifications of Messenger:
Tools > Options > Alerts & Sounds > Display alerts when contacts come online
Tools > Options > Alerts & Sounds > Sounds > Contact Signs In
2) Select the notifications you wish for the contacts you wish in Messenger Plus! Live:
Plus! > Preferences > Customize! > Events Notifications > Add...
a) wizard screen 1: select "notify for selected contacts" and select your special contact friends
b) wizard screen 2: select the event you want a notification for.
c) wizard screen 3: enable "display popup notification" and enable "play a sound"
d) do this for each event you want a notification for...
of course you can also make custom notification for individual contacts and even assign a different sound for each and every contact, etc...
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For MSN Messenger 7.x or below with Messenger Plus! 3:
see "
CookieRevised's reply to Feature Request: Selective popup/login"
see "
CookieRevised's reply to Sign-in Toasts"
see "
CookieRevised's reply to Notification levels"