Hello there,
I have a strong feeling that you have an interview invitation. I received one last Tuesday (12/15) which had subject line "Rutgers Molecular Biosciences Virtual Campus Visit". It was an invitation for interview. As this was a personalized e-mail with a letter attachment having my name and address, I am assuming that they just sent you Save the Date right now and after the holidays would draft a letter to send an official invite. Hoping for the best.