ISERROR()

Google Sheets: match() Extended with join, filter, and iserror formulas to create a comma-separated list of results Scenario: Your sent an email to the recipients in Column A. Now you need to send the same email to the list in Column C BUT you want to be sure no one on that list already received the email (i.e., be sure no one is in Column C and Column A) Use Match, join, filter, and iserror formulas to create a comma-separate list of the new email addresses you need to send the next email to.