Form Postman add-on for Google Forms: The backup-sender function is available in the free edition since July 21, 2016.
Now your Form can send up to thousands of emails per day with this role.
How does it work and how to set up it:
The first, assuming that A, B, C Gmails are the collaborators of your Google Form.
– The A Gmail is set up in Form Postman as the primary sender (not checked as backup sender );
– The B Gmail should be set as the backup of the A Gmail (Backup sender: checked , A Gmail be selected in the drop-down list );
– The C Gmail should be set as the backup of the B Gmail (Backup sender: checked , B Gmail is selected in the drop-down list ), etc …
So then, if the A Gmail can’t send the email since it reached the daily sending quota, the B Gmail will send the email and so on …
Let note that Google permits the editor to add up to 50 collaborators to one form.