'Form Notifications SMTP' add-on can produce "unlimited" professional confirmation and notification emails per day for Google Forms. The emails could be sent via SMTP
Advantages of free version:
- Send from vefified email addresses.
- Full support standard HTML. 
- Sending condition: sends or not based on the user's answers.
- 'SMTP sending' feature help produces "unlimited" emails per day.
- Attach email content as a pdf file (non SMTP sending mode).