FA-76711 / Email MIME structure / Open access

Classify recipients of a delivery status report: successful actions · case 01

Relayed or expanded recipients are reported with an unknown outcome.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The successful actions decision evaluates `action == 'delivered'` where the contract requires `action in ('delivered', 'relayed', 'expanded')`.

THE FAILURE

The successful actions decision evaluates `action == 'delivered'` where the contract requires `action in ('delivered', 'relayed', 'expanded')`.

Unsuccessful approach: Accepting relayed but not expanded still misclassifies alias expansion. The attempted `action in ('delivered', 'relayed')` still disagrees with a fixture.

Case contract

A report is valid only when its type is multipart/report, its report-type parameter (name and value case-insensitive) is delivery-status, and its second part is message/delivery-status or message/global-delivery-status. Each recipient {final, action, status} gets: failed -> hard for status class 5, soft for 4, unknown otherwise; delayed -> delayed; delivered, relayed or expanded -> ok; anything else unknown (actions are case-insensitive and trimmed). has_original is true when a third part is message/rfc822 or text/rfc822-headers. Invalid reports give {valid False, recipients [], has_original False}.

Why this case matters

Bounce processing drives list hygiene and retry decisions; misclassification unsubscribes healthy addresses.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(report):
    t = report['type'].lower()
    params = {k.lower(): v for k, v in report.get('params', {}).items()}
    rt = params.get('report-type', '').lower()
    parts = report.get('parts', [])
    if t != 'multipart/report' or rt != 'delivery-status' or len(parts) < 2 or parts[1]['type'].lower() not in ('message/delivery-status', 'message/global-delivery-status'):
        return {'valid': False, 'recipients': [], 'has_original': False}
    rows = []
    for r in parts[1]['recipients']:
        action = r['action'].strip().lower()
        klass = r['status'].strip()[:1]
        if action == 'failed':
            verdict = 'hard' if klass == '5' else ('soft' if klass == '4' else 'unknown')
        elif action == 'delayed':
            verdict = 'delayed'
        elif action == 'delivered':
            verdict = 'ok'
        else:
            verdict = 'unknown'
        rows.append([r['final'].strip(), verdict])
    orig = len(parts) > 2 and parts[2]['type'].lower() in ('message/rfc822', 'text/rfc822-headers')
    return {'valid': True, 'recipients': rows, 'has_original': orig}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a1@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.1'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd1@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.1'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.1'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 2: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a2@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a2@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.2'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd2@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d2@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.2'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.2'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 3: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a3@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a3@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.3'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd3@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d3@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.3'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.3'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 4: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a4@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a4@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.4'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd4@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d4@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.4'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.4'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 5: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a5@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a5@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.5'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd5@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d5@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.5'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.5'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})]}
for _label, _args, _expected in _CASES[N]:
    check(_label, solve(*_args), _expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
capitalised parameter name	`{'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}`	`{'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}`	Passed
internationalised status part	`{'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}`	`{'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}`	Passed
global message is not a status	`{'has_original': False, 'recipients': [], 'valid': False}`	`{'has_original': False, 'recipients': [], 'valid': False}`	Passed
status class decides	`{'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}`	`{'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}`	Passed
padded capitalised action	`{'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}`	`{'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}`	Passed
relayed and expanded	`{'has_original': False, 'recipients': [['f@x', 'unknown'], ['g@x', 'unknown']], 'valid': True}`	`{'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}`	Failed
not a report	`{'has_original': False, 'recipients': [], 'valid': False}`	`{'has_original': False, 'recipients': [], 'valid': False}`	Passed

SHA-256 / a9fc0ae6777d1fa9a0b2665ccdad1f74f56d919cd02a6db29e27e7e0d10249a5

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(report):
    t = report['type'].lower()
    params = {k.lower(): v for k, v in report.get('params', {}).items()}
    rt = params.get('report-type', '').lower()
    parts = report.get('parts', [])
    if t != 'multipart/report' or rt != 'delivery-status' or len(parts) < 2 or parts[1]['type'].lower() not in ('message/delivery-status', 'message/global-delivery-status'):
        return {'valid': False, 'recipients': [], 'has_original': False}
    rows = []
    for r in parts[1]['recipients']:
        action = r['action'].strip().lower()
        klass = r['status'].strip()[:1]
        if action == 'failed':
            verdict = 'hard' if klass == '5' else ('soft' if klass == '4' else 'unknown')
        elif action == 'delayed':
            verdict = 'delayed'
        elif action in ('delivered', 'relayed'):
            verdict = 'ok'
        else:
            verdict = 'unknown'
        rows.append([r['final'].strip(), verdict])
    orig = len(parts) > 2 and parts[2]['type'].lower() in ('message/rfc822', 'text/rfc822-headers')
    return {'valid': True, 'recipients': rows, 'has_original': orig}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a1@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.1'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd1@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.1'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.1'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 2: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a2@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a2@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.2'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd2@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d2@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.2'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.2'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 3: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a3@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a3@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.3'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd3@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d3@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.3'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.3'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 4: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a4@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a4@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.4'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd4@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d4@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.4'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.4'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})], 5: [('capitalised parameter name', ({'type': 'multipart/report', 'params': {'Report-Type': 'Delivery-Status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'a5@x', 'action': 'failed', 'status': '5.1.1'}]}, {'type': 'message/rfc822'}]},), {'has_original': True, 'recipients': [['a5@x', 'hard']], 'valid': True}), ('internationalised status part', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global-delivery-status', 'recipients': [{'final': 'b@x', 'action': 'delayed', 'status': '4.4.5'}]}]},), {'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}), ('global message is not a status', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/global', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False}), ('status class decides', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'c@x', 'action': 'failed', 'status': '4.2.2'}, {'final': 'd5@x', 'action': 'failed', 'status': '2.0.0'}]}]},), {'has_original': False, 'recipients': [['c@x', 'soft'], ['d5@x', 'unknown']], 'valid': True}), ('padded capitalised action', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': ' e@x ', 'action': ' Failed ', 'status': ' 5.7.5'}]}, {'type': 'text/rfc822-headers'}]},), {'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}), ('relayed and expanded', ({'type': 'multipart/report', 'params': {'report-type': 'delivery-status'}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': [{'final': 'f@x', 'action': 'relayed', 'status': '2.0.0'}, {'final': 'g@x', 'action': 'expanded', 'status': '2.0.5'}]}]},), {'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}), ('not a report', ({'type': 'multipart/mixed', 'params': {}, 'parts': [{'type': 'text/plain'}, {'type': 'message/delivery-status', 'recipients': []}]},), {'has_original': False, 'recipients': [], 'valid': False})]}
for _label, _args, _expected in _CASES[N]:
    check(_label, solve(*_args), _expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
capitalised parameter name	`{'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}`	`{'has_original': True, 'recipients': [['a1@x', 'hard']], 'valid': True}`	Passed
internationalised status part	`{'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}`	`{'has_original': False, 'recipients': [['b@x', 'delayed']], 'valid': True}`	Passed
global message is not a status	`{'has_original': False, 'recipients': [], 'valid': False}`	`{'has_original': False, 'recipients': [], 'valid': False}`	Passed
status class decides	`{'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}`	`{'has_original': False, 'recipients': [['c@x', 'soft'], ['d1@x', 'unknown']], 'valid': True}`	Passed
padded capitalised action	`{'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}`	`{'has_original': True, 'recipients': [['e@x', 'hard']], 'valid': True}`	Passed
relayed and expanded	`{'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'unknown']], 'valid': True}`	`{'has_original': False, 'recipients': [['f@x', 'ok'], ['g@x', 'ok']], 'valid': True}`	Failed
not a report	`{'has_original': False, 'recipients': [], 'valid': False}`	`{'has_original': False, 'recipients': [], 'valid': False}`	Passed

SHA-256 / 3f462808b7cc1f1da3015d54fbc304575aa12461fccf18bdcf39ed949692fbb0

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

Stipulated offline model over pre-parsed MIME dictionaries; not a conforming MIME parser, generator or mail client. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:49:18.719743+00:00.

Case digest / fdf28f2370a4b80ed057c0aa469de837aa1c77a9e1791b19e6825712b5fbf94b