I'm thinking mailman3 should probably keep a list of user bounces. So that
when a user finds out he got unsubscribed, and logs into the interface,
mailman could shown him the evidence on why it got disabled: «see. the last
dozen emails I sent you, at dates D₁... D₁₂ failed with reason "no such
user", "mailbox is full", "i'm a teapot", "This looks
like spam"... What
did you expect me to do if you don't accept my mails?» So that the user
could confront their mail provider on why it is rejecting the emails he
wants to receive.
Best regards
PS: Join me to the list of guys congratulating a good work on migrating the
lists!