This may sound like many other questions - but it's slightly different and I can't formulate an answer.
I have "Tasks" in column A, "Person Responsible" for task in column B, "Email" in column C, and Column D is blank for tracking completion.
When an edit is made to a cell in Column D( like an "X" for completed), I want send an email to the address specified in the corresponding row, with the corresponding task in the email subject/body.
Here is a link to a Google Spreadsheet to help illustrate