[quote=Brand]
Illusionists can, since the school of Illusion has to do with any spells affecting the mind (including mind reading, so they would read your mind to know you're a mage), but otherwise no.
[/quote]

And if I recall correctly, there are no current magic users of the illusionist type, meaning no one could find out anyone else is a mage without seeing their magic first hand. Though I could be wrong, my work schedule keeps me in a state of mind where I'm prone to miss a few details (closing/night shifts = nocturnal schedule for me lol)