An Anonymous Letter, Return Address: Wonderland!

"You're caught in Wonderland, dear friend... Forced to drink, thus forced to play. There's no more sense of yesterday. You're here now, and now that you're here, You have to play, the rules are clear. If you can guess who wrote you the letter, And have successfully filled your vial, Only then can you leave, to go where ever. Only then have you won, free of trial." ;)