Take the Ominous Letter to Force Commander Danath Trollbane at Honor Hold in Hellfire Peninsula.
Giving the lifeless form of Vazruden the Herald the once-over, you discover a rolled letter, its seal yet unbroken. An elaborate "I" is pressed within the blood-red ink. Cracking the note open, the message that you read is most disturbing.
Force Commander Danath Trollbane back at Honor Hold will definitely want to take a look at this!