. . . she's also waaaay too forward, and too loud in the recording. If you look at the score, Mahler writes piano for the mezzo (or baritone) throughout the entire length of "Der Abschied", with the exception of just two crescendo markings. Nowhere does he mark forte for the singer. It's not a giant mezzo aria. If anything, the singer should just deliver the text; sing in-tune and on time; put in a few nice inflections, and then just stay the hell out of the way of Mahler's incredible orchestration. Listen to how Michelle De Young handles the entire ending section on Eiji Oue's quite underrated recording of "Das Lied". That's how it's marked.
