Mandrill emails sent to Hotmail go to the spam

THE SITUATION:

Hello guys. I am registered with Mandrillapp and everything is working fine. I can send and receive emails from my app.

I have just this issue: The emails sent to Hotmail end up in the spam.

THE QUESTION:

How can make sure that the emails directed towards Hotmail go properly to the inbox? Did somebody encounter this issue before?

Thank you very much!