GatewayEmailInboundDto

{
    "channelId": "550e8400-e29b-41d4-a716-446655440000",
    "rawBase64": "RnJvbTogSm9obiA8am9obkBleGFtcGxlLmNvbT4uLi4=",
    "uid": "12345",
    "messageId": "<abc@mailer.example>",
    "gatewayMessageId": "gw-email-123",
    "receivedAt": "2026-03-05T10:00:00.000Z",
    "skipAgentAssignment": false
}