For many scenarios, it's clear cut whether a bounce is a hard bounceI'm curious about the cases you find uncertain.
Yahoo Groups's handling of bounces was once very much like you describe, with the hard/soft distinction being made strictly by the response code (4xy is soft, 5xy is hard), per the email RFC.
But then a couple years back some email services started using 5xy codes when rejecting due to RBL results (Realtime Black List, or Dynamic Black List) - which made a mess of things. At that point Yahoo Groups started treating all bounces as "soft".
Is that the circumstance you're concerned with? And are you using some kind of heuristic to further discriminate among 5xy responses?
If we receive soft bounces for someone for 8 days, we also changeIn the case of an RBL problem the member may be having some fraction of the messages bounced, and the rest delivered. How does your mechanism work in such a case? Is a single bounce in each of eight consecutive days sufficient to change the status, or does it require eight days with all messages bounced, or something in between?
If we receive no response after sending 4 of these bounce reports toIf such an address happens to be the sole owner of a group, what happens to the group (if anything)?