Don't know whether this helps, but a much quicker way of splitting up
your addresses in Excel is to select the column and use the "text to
column" feature under the "data" menu. Just set the delimiter character
to other and put in the @. (Make sure the column to the left of the one
containing your addresses is blank.) The first part of the address  will
be in the first column, and everything after the @ will appear in the
second column.