One of the last major subsystems that I need to get working in Mailman 3 is bounce processing. This is different than bounce detection, which has been successfully ported from Mailman 2, but doesn't differ in any significant way. The question I am thinking about now is what to do with a bounce once we detect one.
There are a couple of interesting things in MM3 that makes it different from MM2. In MM3, users and addresses are global to the system, while membership is specific to a mailing list. This means if we register a bounce on an address, we can have that score affect the address's subscription to all relevant mailing list. We can also do things like automatically roll over to another registered and validated email address for that user, if there is one, or at least send notifications to the other address.
There's also the question about how all the bounce scores are managed, and the knobs you as a list administrator can tweak to control how and when things happen based on the score. Reporting and logging are also part of the plan.
Because MM3 uses a relational database underneath the hood, my plan is to have a single table that only appends new bounce events. That way, Mailman will have a permanent record of every bounce that occurred. Exactly what information we can or should put in that table is up for discussion. I do plan also to keep all bounce messages in MM3's "message store" so that postmortem debugging is easier.
Because I'm just starting to think about all this, I wanted to throw this out to the list to get your feedback on things you'd like to see. What is it about MM2's bounce processing that you like? What don't you like? What MM2 bounce features can you do without? What would you like to see added?
Any and all feedback is welcome. -Barry