[jeromegv]

aMSN had this feature because the MSN protocol would establish a connection as soon as a you opened a chat window (before you started typing!) in order to be able to retrieve the display picture from the other user. So you would be able to know that someone opened a chat window but decided against starting to type (or haven't decided quite yet they would want to type).

This is documented in this old FAQ https://github.com/Kjir/amsn/blob/master/amsn/FAQ

(Former aMSN developer)

I admit now this is creepy.

[shultays]

Huh, was msn fetching the profile picture from other perso (p2p?), and not from msn servers?

[GekkePrutser]

It was early days for IM and I guess storage was expensive.

Early ICQ didn't even store the contact list on the server so you had different contacts on every PC.