title: Extract unique email addresses from excel column
body: <p>I have a list of 250k email addresses. The email addresses are in column A of the worksheet. I am trying to extract every email address that is not a duplicate on this list into it's own column (C). Since 70-75% of these email addresses are duplicates it should leave me with about 40k unique email addresses. </p>
  
  <p>Any help on this would be much appreciated. </p>