About ProtocolErrors in bounce_classifier

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1

Hi teams
When I was looking at bounce class, I looked at iana.toml.
where the ProtocolErrors is

ProtocolErrors = [
  "^\\d{3} [45]\\.5\\.\\d+ ", # misc protocol error
  "^\\d{3} [45]\\.6\\.\\d+ ", # content negotiation protocol error
]

Regarding this, the 5.5.x enhancement code that I often encounter in my daily life is a normal error, not a protocolErrors one.
For example:

"response": {
    "code": 550,
    "enhanced_code": {
        "class": 5,
        "detail": 0,
        "subject": 5
    },
    "content": "Requested action not taken: mailbox unavailable (S2017062302). [DS3PEPF000099D4.namprd04.prod.outlook.com 2025-06-30T17:07:27.735Z 08DDB7B7476E7A1B])",
    "command": "RCPT TO:<xxxx@outlook.jp>\r\n"
}

The question is whether attribution to ProtocolErrors is appropriate.
Of course, I can revise it through revision, but I wonder if you have deeper considerations

3

Each mail provider treats the enhance code differently, and it is really difficult to unify

4

Discord This topic will be the solution. Before asking questions, I should look it up.