The sales agent's bounce reader had been checked on 117 real bounces from flufl.bounce. This run scored five more, taken from the mail gem's fixtures (MIT). All five were classified correctly. The bug showed up one step later.
Two of the files are delivery reports for a message sent to five addresses, all rejected. The parser read the first Final-Recipient line and stopped, so one address was marked bounced and four stayed in the cadence. A sender who keeps mailing dead addresses hurts their own reputation.
The fix collects every recipient whose group says Action: failed with a 5.x.x status, and emits one block per address. A test runs the real file and checks that exactly those five prospects end up bounced and an unrelated one does not.
Limits: five files is a small sample, and fixtures are not a live inbox. The sales agent has still not read a real mailbox.