Email List Opt-Out Removal Processing Application

Due to the New Bill C-27 Passed in Canada, it is not legal to send email to individuals the have requested to be removed from our list. I need an application written in vb.net that will take two files, 1 being the master email list which can vary from 1,000,000 to 10,000,000 email addresses ( approx 50mb - 200mb size ) and the other list being a list of individuals who would like to be removed. It just needs to be a straight comparison, if entry in list2 exists in master list, remove it from master. Once the remove list has been processed it will save it as a new text file. No fancy looking GUI needed, just simple stuff and the source. I will finish the GUI myself in Visual Studio. As I stated before, it needs to be programmed in vb.net and it needs to be fast and efficient as it deals with large lists.