How to use onEdit function to trigger an email - google-apps-script

Question

I'm very new to script writing, but I'm trying to set up a script to send an email once a certain cell (A4) is populated within a certain sheet.
The trouble I'm having is getting the script to trigger - I understand that running it when not in the spreadsheet generates an error, I get no error message, but no email appears to be sent using this code:
function onEdit(e) {
var name = SpreadsheetApp.getActiveSpreadsheet().getName();
var cell = e.range.getA1Notation();
var spreadSheet = e.source;
var sheet = spreadSheet.getSheetByName('Scanned');
var range = getRange('A4');
var column = e.range.getColumn();
var row = e.range.getRow();
if(sheet == 'Scanned' && column == 1 && row == 4)
MailApp.sendEmail('joey#gmail.com', 'Tipping Notification: '+(name), 'Notification email body '+(name));
}

Answer 1

An onEdit trigger always requires a 'manual' edit of the spreadsheet. If the spreadsheet(cell) is populated by a formula, it will not fire the onEdit trigger.
Also, in order to send emails, you'll have to use an installable onEdit trigger. Simple onEdit triggers cannot access services that require authorization.

Answer 2

There are some restrictions for using simple trigger, One is simple trigger cannot access services that require authorization. For example, a simple trigger cannot send an email because the Gmail service requires authorization.
In order to use services that requires authorization, you need to create an Installable trigger. See this link on how to create Installable Trigger.
Also, getSheetByName() returns a Sheet Object and not the name of the edited Sheet. This causes your code to skip sending email.
Try this:
Code:
function onEditA4(e) {
var editedSheet = e.range.getSheet().getName();
var editedCell = e.range.getA1Notation();
var name = e.source.getName();
if(editedSheet == 'Scanned' && editedCell == "A4")
MailApp.sendEmail('insert email here', 'Tipping Notification: '+(name), 'Notification email body '+(name));
}
Example Trigger: