Shoutbox

I noticed something. Let me explain how I noticed it:

I backed up all of my contacts with Messenger's menu "Export Contacts". Then I deleted all contacts. Then I imported that contacts file again. When I imported it, all of my contacts appeared with their email addresses in my contact list. Then as people come online from one day to another day, display names of those contacts' who came online were saved in my local computer (not in the server). So I always saw their last used display names properly in my lcoal computer even if they are offline sometimes. However, yesterday I went to school and signin Messenger on a computer in a computer laboratory there. When I signed in, I believed I will see all of my OFFline contacts' email addresses only, not their display names because I believed display names weren't stored at the server. I confirmed this statement for all of my offline contacts except only ONE contact (not to mention I already get online contacts' display names) I wondered what is different with this ONE contact, why I saw his display name even he is offline. I must have seen his e-mail address like all other offline contacts. I came home and investigated the issue and realized that I am receiving contact updates from only that ONE contact. Then I subscribed all of my contacts' updates and after 5 minutes I unsubsribed again but now whereever I signin, I see their display names which I saw while subsribing. So now I can safely say that "Subscription to contacts' updates" has something to do with this display name issue but I couldn't understand yet how it works exactly.