How to make 1 Unique Email list from from 2 other email lists (one list minus the other)

Ok this is a bit weird, but imagine this..

In Column A I have 500 email addresses.
In Column B I have 2000 email addresses.


Now in Column C, I want to have all the email addresses in Column B MINUS all the email addresses in Column A.


IE: So basically if Column B had 300 of the same email addresses in Column A, then Column C will have 1,700 email addresses (2,000 - 3000) = 1,7000.

Does anyone know how to do this? I'm so confused right now..