Email Quota Limits
How many emails/certificates can I send per day? What happens if I exceed that?
If you're using a regular Gmail account, Add-ons like Certify'em can send only up to 100 emails (certificates) per day*. If you're using a paid G Suite account, Certify'em can send up to 1,500 emails (certificates) per user per day*. These limits are imposed by Google, and not by Certify'em. Note that if you choose to send emails for exam attempts (an email is sent even when exam-takers don't pass), then those emails also count towards this limit.
If you were to reach the limit, Certify'em would no longer be able to send out emails to exam-takers. To avoid the confusion this may cause, Certify'em will try to automatically disable access to your exam if it detects you are getting close to this daily limit. This is to ensure that exam-takers can always receive a certificate if they take your exam. Users visiting your exam will see a message like "This form is no longer accepting responses".
Certify'em will check back every hour until your daily email send quota from Google has reset, at which point it will try to re-enable certification on your exam. You will not be notified again by email when certification is re-enabled.
* Assumes no other installed Add-ons that are also sharing this daily email quota. The higher G Suite limit of 1,500 can take several billing cycles to kick in for new customers.