Hi
If you check 'Suppress Multiple Alerts of This Rule' then also you should receive at-least one email.
Normally in production environment we check that option because it avoids creating duplicate alerts fro the same type of error in same time frame.
Check 'Suppress Multiple Alerts of This Rule' and make sure that all the emails are confirmed in the alert inbox. Just go to alert inbox and read the alert message.
Once you do that you will receive alert for the new message failure in AE.