¿Se admite enviar una copia de un correo electrónico a una dirección de correo electrónico de categoría?

Tengo configurada una categoría para crear temas mediante el contenedor Docker de receptor de correo simple. Esto funciona correctamente si el correo personalizado está en el campo ‘para’, pero puedo imaginar que los usuarios quieran agregar la dirección como copia (CC) al responder a una consulta (y así crear un nuevo tema). Sin embargo, en la actualidad esto genera un rebote duro. El correo sin procesar se muestra a continuación, por si ayuda a diagnosticar el problema.

Original Message Headers
ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
 b=RMdzOATFmy5T332lLPqvXDhUIG4noW+3JrFlhdHVgi4vgFkEgekprSnuttXd9nXVNC0e1zokeBWg6gX7HufnIawNoG8fTg0Mdi2CibU9qvWHuzNv62yMrQtGKdSQgAoMu8G+boXgoedt3bXaeYcWQnNNFazRo0Zv/9ZhwkIgf6nL8i+QqgCEV6rHln8TouZUaOnpiFfpf1eQsnCS2jmja24e5AoGsr/BckNS4A2GnC43mItHB4UcS+nTOe+9DQUYlDyYGXSW0z71NdQ0Wr6rp9Jxqi36N0ttEOicnquUJjVQLSUyLxSA+Jaeyx0mUO8A5T5qzPbae7hWHtRT03L0bw==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com;
 s=arcselector9901;
 h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
 bh=VcKdFTK0IkrHVbOeqCF3xRkl6lH5ADRsiNsPwcYF3MM=;
 b=AimZ+oZMcD1yQeWLzCIrVYzkCE+KAd2ALmCoEa7QACVTitoTwH4dp7//YFI/ZZfbgsYOQyFg9VzSR+77gxqpKS+xZJGxz1qy3wWi1iPtPslwTTsP+dBj0//IV0aI6Z1xPcGR9p5pt3D8wuMJZB/JAbF7vmYxYP27+dziPg5Q4WR/0mcZqAChR1jL9LYFhrHOnO+F4Pz6zXvtly050+MdyRJQXFgVuGgsLsoPbLPeOH3d07KfyNqm535NAFebuTB5nKxhwDBVKCD/dlBrD7Typ9ZcIiLe6zGlmUpcSO6V5zVQd4GI024xglRiB/ZHBQ+hsDkJ8FbVBBoIm8deqabHEQ==
ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass
 smtp.mailfrom=sendingdomain.com; dmarc=pass action=none
 header.from=sendingdomain.com; dkim=pass header.d=sendingdomain.com; arc=none
Received: from VI1PR03MB3680.eurprd03.prod.outlook.com (2603:10a6:803:36::18)
 by VI1PR03MB6382.eurprd03.prod.outlook.com (2603:10a6:800:194::18) with
 Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3933.31; Wed, 17 Mar
 2021 17:26:09 +0000
Received: from VI1PR03MB3680.eurprd03.prod.outlook.com
 ([fe80::18bc:4b2b:7c8e:a29a]) by VI1PR03MB3680.eurprd03.prod.outlook.com
 ([fe80::18bc:4b2b:7c8e:a29a%3]) with mapi id 15.20.3955.018; Wed, 17 Mar 2021
 17:26:09 +0000
From: Ben  <ben@sendingdomain.com>
To: Ben  <ben@gmail.com>
CC: "inboundaddress@discoursedomain.net" <inboundaddress@discoursedomain.net>
Subject: Test 3
Thread-Topic: Test 3
Thread-Index: AQHXG1KeYnOLfgK5wkiegVvRgKHEGQ==
Date: Wed, 17 Mar 2021 17:26:08 +0000
Message-ID: <0A90CCDB-EA9F-4F49-BE84-C5DF00991E2C@sendingdomain.com>
Accept-Language: en-GB, es-MX, fr-FR, en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-mailer: Apple Mail (2.3608.120.23.2.4)
authentication-results: gmail.com; dkim=none (message not signed)
 header.d=none;gmail.com; dmarc=none action=none header.from=sendingdomain.com;
x-originating-ip: [2a02:c7f:5842:5b00:4d67:3770:8213:2dcc]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: c3f4160b-b9c6-444f-d45f-08d8e969c0f6
x-ms-traffictypediagnostic: VI1PR03MB6382:
x-microsoft-antispam-prvs: <VI1PR03MB63829F3EC03AE93C4723DA6DCD6A9@VI1PR03MB6382.eurprd03.prod.outlook.com>
x-ms-oob-tlc-oobclassifiers: OLM:1728;
x-ms-exchange-senderadcheck: 1
x-microsoft-antispam: BCL:0;
x-microsoft-antispam-message-info: /07cGYBxOLLKVBAaGVXZOTHj/qQwPH9nK90hTHBIdQ+S9gl/hL4bfyxxi5uRN+xDZszsforlspCz3SF84GtfuGs40WOOHgaZuDKG/30t1/ypsRFcYSAwsi6fBnKhDrtjgj2jVgBxVC7J7GbhYPPgFl1+NetljURFvWXauDv1VKK3twaMFDwJnW44Zt9dURFPf1LDpFMKqP5jmYWcEK6B/zVh9gP8VuwzShzzV5wSt8XQEbdCj6oRSV2rfkOm124bbe9OBbVTD7jkcOPVONVXQXwyw0uPKa0L6bYVQS1HmO6MlHlpOnKBhMmKgo91lfmBMvLoUaBkaCTKXWWLqKVqjVoKx7qSwf1qdVMiaKsiqXw=
x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:VI1PR03MB3680.eurprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(136003)(346002)(376002)(39860400002)(396003)(366004)(6486002)(5660300002)(316002)(7116003)(83380400001)(186003)(8936002)(786003)(6506007)(36756003)(33656002)(66446008)(2616005)(86362001)(4744005)(76116006)(6916009)(66574015)(8676002)(66946007)(478600001)(66556008)(4326008)(6512007)(66476007)(64756008)(71200400001)(44832011)(91956017)(2906002)(45980500001);DIR:OUT;SFP:1101;
x-ms-exchange-transport-forked: True
Content-Type: text/plain; charset="us-ascii"
Content-ID: <6A93DBCCB0EEF8498860DB64F13F9999@eurprd03.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: sendingdomain.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: VI1PR03MB3680.eurprd03.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: c3f4160b-b9c6-444f-d45f-08d8e969c0f6
X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Mar 2021 17:26:08.9885
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 5437e7eb-83fb-4d1a-bfd3-bb247e061bf1
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: ZipWxxH8/rQkcocxo4TQm2UgZMpINIZejK8vG80jsVXgu366SPtfLWFyYlwCxSW6Rbsj+CU+utKqNXOKtXYPLi2on82DgjFUu7sGjzCxcpo=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR03MB6382
Reporting-MTA: dns;VI1PR03MB6382.eurprd03.prod.outlook.com
Received-From-MTA: dns;VI1PR03MB3680.eurprd03.prod.outlook.com
Arrival-Date: Wed, 17 Mar 2021 17:26:09 +0000

Final-Recipient: rfc822;inboundaddress@discoursedomain.net
Action: failed
Status: 5.1.1
Diagnostic-Code: smtp;550 5.1.1 Requested action not taken: mailbox unavailable
Remote-MTA: dns;inbound-smtp.us-east-1.amazonaws.com
X-Display-Name: inboundaddress@discoursedomain.net