Dear Mallika, I don't like you.
Why do you not like me?
You don't look good at all
You shouldn't flat out tell someone that you don't like them. If you have a way to word that you don't like someone in a more polite manner then you should take that opportunity.
Imagine me sending a text message and nothing else. That's what Mallika's face looks like.
That is extremely rude. If you don't like the way she looks than keep it to yourself, there is no reason to text her that.