Moodle notification - Task failed: Send user digests

One of our Moodle instances showed this in the task logs:

SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/TroubleshootingSMTP server error: QUIT command failed 

Detail: Too many login attempts, please try again later. For more information,

go to https://support.google.com/mail/answer/7126229 

This could have been due to sending each email with a separate login - I have changed the SMTP session limit to 90 instead of 1 (which would have made the server log in repeatedly for each email).

Another possibility is that one of our development servers is also using the same email id for sending, and that is causing a "too many connections" error which is what the google support page linked above talks about. So, I created a separate email account for that server to send emails from the development server to prevent these errors from happening.