Not an actual anniversary email, but a congratulations note I sent two recipients of a promotion at my company.
Congratulations, <NAME> and <NAME>! With your new roles come increased responsibilities. Tasks, if you will. Toils, like the heroes in some Homeric epic. Deep within the confines of the earth, the hidden things sleep. Impossible beings that should not exist. Things that by our current understanding of the sciences cannot exist. The great weeping sores that line their bodies weep sweet lacrima. When ingested, this cloudy fluid opens our minds to strange new vistas and terrifying cosmic truths that unwind human sanity and send us into a spiral of madness from whence there is no return. To sup from their wounds is to blow open the doors of perception and wrench your third eye open in blood and pain. To light your every nerve with electric current and burn away any pretense you maintain about your place in this world. You cannot call yourself fully human once you have tasted their alien fruit.
Of course, such things must be made to slumber. They are fang and claw and multitudes of limbs and mouths that will surely seek to consume all that lies before them. They hunger, and they sleep fitfully. You must descend beneath the earth, into the lightless subterranean caverns and sing them a siren song of screams of pain and terror. All that soothes these monsters are the sounds of strife and the scent of bloodshed. The taste of fear. Conflict is, to them, a sweet lullaby that gently lulls them back into complacency. Dreamless sleep.
In time you shall grow accustomed to your new home. Your eyes will fog and go dark in the depths. You will no longer need sight. You will navigate by the scent of the sleeping ones and the sound of their vast mass shifting, signaling the need for your ministrations. Eventually, as you continue to subsist on the fungus found in their caverns, a fungus fed by the secretions of the sleepers, you will begin your transformation. Finally, one day you will take your place among them, joining their ranks as we send new acolytes into that hellish chamber of lament.