Meanwhile, as admin, I have been receiving notifications about uncaught bounces from mailman with permanent failures on about 6 yahoo.com emails.
Bounce processing is supported only on mailman 3.3.1 and above.
I am going to remove these bouncing emails from the list next week unless someone objects.
I have unsubscribed these emails. There are 10 of them and I have a backup of these addresses.
Akshay