Daily Email Limit
Form Email Notifications uses Google Api to send emails for notification.Google specifies how many emails you can send per day depending on the type of account you own with Google.
A gmail.com account may be able to send upto 200 emails per day.
However Google workspace accounts may be able to send up to 2000 emails per day.
You can find relevant google quota documentation by visiting Quotas For Google Services .Look for Email recipients per day or Email recipients per day within domain
If you send an email to multiple recipients the quota will reduce by the number of recipients and not the number of emails you send.
This is completely managed by google and may change any time. You can find the details by visiting Gmail Sending Limits in Google Workspace
Including attachments in Email will reduce your quota as per google
Your daily quota is shared among all the add-ons.This means if you are using other add-ons or scripts to send emails all of them will impact your daily quota
The remaining quota shown at a particular time may not be exact as google may take time to calculate this quota.
You may consider using Apps to notify yourself or team to reduce Email volumes.
You can use this option whenever you want to start with a clean state.This will remove all the data the add-on may have created or stored for this form.
Clicking the reset button will delete all processors and remove all the triggers.
What is Trigger
Form Email Notifications creates triggers which google uses to invoke form notify code when a new response comes in.
When you hit the reset button Form Email Notifications will delete the trigger as well along with processor.The result is Form Email Notifications won't get to know when a new response comes in.