Email address in excel spreadsheet
 

I inherited a spreadsheet to maintain that contains a column with contact
email addresses. Some of the values will actually take you to a new email
address (as they should) but other values are just like text. Also, when I
need to change an email address and after typing in the new value, it still
"points" to the old address previously stored in the cell.

I have researched and tried fixes but to no avail. Could someone please
tell me how to correct these cells.