Hi,
I will try to explain this another way.
iChat can join or rather use several of the Instant Messages Service that are out there.
When iChat was created it could only join the AIM service and Apple made and Agreement with AIM that the Apple IDs ending @mac.com were recognised as valid AIM names.
Later when Apple changed to MobileMe @me.com ending names were added to the Agreement.
This means you can have an AIM Name or an Apple ID ending in @mac.com or @me.com and you can add Buddies to that Buddy List that have those same type names.
In this Pic I have changed My Buddy list to show Screen Names only (and then edited those)
I have indicated one of each type of name that is valid with this Buddy List.
The AIM registration page is here
The Main part looks like this
You can enter the "Username" part or you can enter any other email you have.
This way it is possible that you can have a Buddy with an @yahoo.com name as an AIM Buddy as in your later pic.
There is another way. If they are on PCs then the latest version of AIM for PCs allows them to add GoogleTalk and FaceBook Buddies. The Mac Version also seems to do this now.
It also seems that some of the Social Networking sites are also connecting up with other Instant Message Services.
Jabber (Google and Facebook included)
The other main service that iChat can join is Jabber.
It has been able to do this since iChat 3.
The Names or IDs people have come from a range of Jabber Servers.
People runnning those servers set them up so that they can contact other servers and by doing so provide a network.
A person would join one of these servers and end up with an ID that was in the form of Username@JabberServerName.com (so for an example I could set up the ID of ralph at a server called jabberchat.com and my ID in full would beralph@jabberchat.com)
Very few servers also offer email services
Most Jabber server need you to register via Jabber application.
There are a couple of exceptions to this.
Jabber Australia (http://www.jabber.org.au/) allows you to register via a Web Browser.
Both Google and Facebook allow you to Enable Talk or Chat on the account settings there and then use the name in a Jabber able application.
Google do not stick to the naming format that every other Jabber Server does.
They call their jabber Server talk.google.com whilst a ID from there is your Googlemail ID.
This means that in iChat you have ot set up a Google Buddy list differently or at least separately to account for this.
In iChat 3 this was a Manual change (Specific iChat 3 Instructions)
So....
Buddy Names and IDs can look like emails (in some cases they are email addresses as well)
In most cases these names and IDs can only be used with one service although that is becoming more and more blurred.
I have not seen email addresses ending is ss or do or oa
I would not tend to look at a Jabber server that was not using English so I also don't know of any jabber servers that end with those letters.
Although this is a very small list it does not seem to list any Servers with those Endings
This would appear to indicate that you added what were random email addresses to your Google List.
AS Yahoo names would not normally appear in an AIM (@me.com) list I suggest you have done the same there.
8:45 PM Saturday; May 5, 2012
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