Google App Script to send welcome mail to Google Form signups

HOW TO USE THE SCRIPT

1. Go to Tools > Script Editor from the "Responses" spreadsheet
2. Copy/Paste the code in script.js into the editor
3. Click the save icon to save the script
4. Go to Edit > Current Project's Triggers
5. In the "Add Trigger for Mail to Volunteer" popup, the function is automatically selected since it's the only function in the script. Choose 'Head' for deployment; Event source: "The spreadsheet", Event type: "On form Submit"; Failure notification: "Daily" I added a marker on colunm 'Z' to determine if a mail has been sent already, in case a user resubmits the form