A cool wash cloth on a feverish head would be a very comforting sensation, so the simile is used to convey that the email contact was also comforting.
Context: As she felt her fingertips touch the apparition, the sensation was rather comforting.
Hypothesis: As her fingertips touch the apparition, the sensation overtaking her is like a cool wash cloth on a feverish head.

Is the hypothesis incorrect? (Yes, no, or unknown)?