I am a GSoC student working on Syster's custom version of Mailman. I am trying to record the stats for the number of users unsubscribed through different means like email-confirmation, admin mass removal , etc. More details here: http://systers.org/wiki/doku.php/f_dlist_stats_scripts
In the mailman source code, I don't see the provision to process an unsubscription request through email, i.e, when a user sends an email with the subject 'Unsubscribe'. It is possible that the provision is there and I have missed it. If so, please correct me.
I tried to check for myself if that functionality is there by sending an email with the subject "unsubscribe", but that just appears in the held messages of the admin interface waiting for moderator action.
Is there an existing functionality for unsubscription through email in Mailman 3. If yes, what is its implementation design (just a brief overview).