Hi

Select the column. Menu Data Filter Advanced filter, there's a "show
unique items only" checkbox.

It will not mark the duplicates, it will hide them, which I suspect may be
your goal. If not, or anyway, see Chip's page
http://www.cpearson.com/excel/duplicat.htm

HTH. Best wishes Harald

"Ed P" skrev i melding
...
I have a list of e-mail addresses. I want to find all the duplicates. I
have
sorted the list but the list is extremly long.
I have not found an effective method for doing this. I want the result to
show me where those duplicates occur.
Can anyone help me?
Thank you