Suspend some mail notification correponding to a sender I wish to disable some mail notifications let's say, the ones coming from a mailing list named TEST. Is there a way to do it or the notifications are all enabled/disabled at the same time ?

In the rules section I see how to make a notification appears but I don't see any way to hide it...
Try to set the notifications prefs in Mail > Preferences > General 
You'll see 2 settings to set the behaviour of the notifications.
You'll can set the notification for all emails, only for your contacts or only for the VIP senders you've defined.

Depends of the OS X version you have, this settings can be there or not.