Hello there.
the situation is. i have an excel file with 10K mail address. now i would like to add some more email address on that file. but i dont want any double entry with it. If i add any entry which is already in there only that entry will show with some different color or something so i can understand its already there. i dont want any email address will be erresed autometically. it will show me which i need work.

Thank you.