This above solved my issue with emails/notifications from my ISY. Despite hours of trying different DNS, email accounts, timeouts etc. could not get it to work until i created 'App password' in my google account settings (Security\Signing in to Google\App passwords)
Summary;
-Had no idea Google '2-factor' authentication could affect this
-Had no idea Google account had 'App Password' feature
-Created 16 char 'App Password' & copy/pasted into ISY: Configuration\Emails/Notifications\Settings/Groups\SMTP Settings:Password
Thanks Geddy!!