I'm working on a script that uses the Gmail API to send email (HTML body) to a list of users via GmailApp.sendEmail() function. After it sends email to 5 users, I get the "Gmail operation not allowed." exception.
I'm not sure if there is something wrong with my script (limits, permissions, ...), or is it something wrong with the Gmail API. I've tried to google for an answer but all I find is that it happens from time to time, which isn't very insightful.
Can someone please explain what this exception means and how to handle it?
Thank you in advance for your assistance!