Beim Versuch testweise eine Email von meinem Outlook-Account an meine T-Online-Adresse zu senden habe ich folgenden Fehler bekommen (Mailbox ist nicht voll):

Delivery has failed to these recipients or groups:

Your message wasn't delivered. Despite repeated attempts to deliver your message, a connection to the remote server couldn't be made.

Contact the recipient by some other means (by phone, for example) and ask them to tell their email admin that it appears that your email system is unable to connecto their email system. Give them the error details shown below. It's likely that the recipient's email admin is the only one who can fix this problem.

For more information and tips to fix this issue see this article: https://go.microsoft.com/fwlink/?LinkId=389361.

Diagnostic information for administrators:

Generating server: AM7EUR06HT213.mail.protection.outlook.com
Receiving server: AM7EUR06HT213.eop-eur06.prod.protection.outlook.com
Total retry attempts: 18

6/4/2021 3:56:16 PM - Server at AM7EUR06HT213.eop-eur06.prod.protection.outlook.com returned '550 5.4.317 Message expired, cannot connect to remote server(421 IP=40.92.16.57 - No more parallel connections from your address allowed)'
6/4/2021 3:51:16 PM - Server at t-online.de (194.25.134.9) returned '450 4.4.317 Cannot connect to remote server [Message=421 IP=40.92.16.57 - No more parallel connections from your address allowed] [LastAttemptedServerName=t-online.de] [LastAttemptedIP=194.25.134.9:25] [AM7EUR06FT043.eop-eur06.prod.protection.outlook.com](421 IP=40.92.16.57 - No more parallel connections from your address allowed)'

Original message headers:

 ARC -Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
 b=hQ45cMBZrxXjD0gdyVwxhu5FDz/qLTa7kNK5L+Dn3T9FZCCGCvtrwFXGaBDSWFD3YvbjYNrU3cikqc/8STshnJ658h2teLcYlXKU0v2dCAMEfXT85eCvpO1a5iA3sxkii751mstw8jvngqLxijtN7w7MT/dsjKDuZhcBKM/NByQL6lzgp6f7Bmyc0iUX0zBubzy8zwE3FZO84yUPF17ZksyKnlDxWONW4LBt5C4SuBC3u6cnrAAuTSuBOKpmNtOqFVMNQJs3Gv5B1r9gn1/gfmlpbpiqkTkuXKO0mwlzXxogY/I47ciV1RT8u0UsPIvrbw/TcZghFC1uir7lN2l3+g==
 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=x5V4JT+GJhBhsgw/lTbWiqhgyAN6WGgSXNChvA67Pb4=;
 b=TaXh1AXART0GY4BWpcS5yemXm5PUATkvCNh1RK8ijAfbPEBHnnzzdLbvDHIktMeawtGkLnRb9wWhu53e43rfgejaW2Rb1q4av7dkD28aGI+/M1M+TocB8SA8coloTon9UQriq910Rt9OJeG/f9KuKJXXj0A6MdS/vaOKe7MEClEqTlF9hM275NrPzbnzR5ecc8altLmPdUach5pZVRXu+0MIC6nTkbs7KToCer2f6oMspCjxBhFLQcDS0RL/NC61JXqUD8dJI4sG4ezX4vQ+CvmapLNibgpzvS5LlFBN1MM9EKrZ+QkiURs4d/uKc1GFxksRT7c/F6CTxSQpBRDw0g==
 ARC -Authentication-Results: i=1; mx.microsoft.com 1; spf=none; dmarc=none;
 dkim=none; arc=none
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=outlook.com;
 s=selector1;
 h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
 bh=x5V4JT+GJhBhsgw/lTbWiqhgyAN6WGgSXNChvA67Pb4=;
 b=SrMZty2Bkwnp51m8rzxGyGp6u7D+VmTkXJrWNDG/ns3upBLZpcTgMlYPTlW3t0EzctDfbmBtcJOQeNi69CxKvnr+CPkALWA7b+8IlmPgaGtmWwGbGVko45eGmUTj6mNEfpTkBZ/TkMt/uVNm9Rqswn9Xx037ero4+a4CPN9O0fHN4xStr1lAaF8WmHQjHp/UcLTv5NLm449/GEtMNk+wGSx1MFhCFhv/cvtgXpd034BpLmr2AB2lZH6sHzb7x1FguZU6aLWFbz+Wk1YWoKlJlcKu7OPl8K+h/xidQLMyDiP11zJAPZIRExxo/S5HgKvgEUAZsKVN/XMkaJdsocTR1w==
Received: from AM7EUR06FT041.eop-eur06.prod.protection.outlook.com
 (2a01:111:e400:fc36::4c) by
 AM7EUR06HT213.eop-eur06.prod.protection.outlook.com (2a01:111:e400:fc36::137)
 with Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4195.18; Thu, 3 Jun
 2021 15:49:47 +0000
Received: from AM8PR04MB7297.eurprd04.prod.outlook.com
 (2a01:111:e400:fc36::44) by AM7EUR06FT041.mail.protection.outlook.com
 (2a01:111:e400:fc36::165) with Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4195.18 via Frontend
 Transport; Thu, 3 Jun 2021 15:49:47 +0000
Received: from AM8PR04MB7297.eurprd04.prod.outlook.com
 ([fe80::b8cc:db83:7b8e:4c4b]) by AM8PR04MB7297.eurprd04.prod.outlook.com
 ([fe80::b8cc:db83:7b8e:4c4b%7]) with mapi id 15.20.4173.030; Thu, 3 Jun 2021
 15:49:47 +0000
From: x
To: y
Subject: Test
Thread-Topic: Test
Thread-Index: AQHXWJAQJRL3OoknSUSe1b7NfMcqfw==
Date: Thu, 3 Jun 2021 15:49:47 +0000
Message-ID: <AM8PR04MB7297FD6E9C6B44728443BDD99B3C9@AM8PR04MB7297.eurprd04.prod.outlook.com>
Accept-Language: en-US, de-DE
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-incomingtopheadermarker: OriginalChecksum:EB1549FB58E0932D260B101B86EB307B42536FC17E7507BC76C9E6367F7C4A14;UpperCasedChecksum:57CAC85933A1538D67A17D08B6C2E50C8AEC02BB7D228ECA055BB0817CF80DE6;SizeAsReceived:6615;Count:42
x-ms-exchange-messagesentrepresentingtype: 1
x-tmn: [l5akgCy2kVxYiUzxa6OCpcjuJHP/uKCn]
x-ms-publictraffictype: Email
x-incomingheadercount: 42
x-eopattributedmessage: 0
x-ms-office365-filtering-correlation-id: 06e50af4-c3bb-44af-e9a1-08d926a736e0
x-ms-traffictypediagnostic: AM7EUR06HT213:
x-microsoft-antispam: BCL:0;
x-microsoft-antispam-message-info: fi+PwcbxBt/7GDPqoyrPecHIkBmV+hmzDN3gfXRwpFUvxom0QGW3r6r3lu1GYIMspES5CbzsJO2KIuqIYCTcr7f9fk93JbPllNZhHKiD1tGe2itt608eMnbzyplZ3GB6
x-ms-exchange-antispam-messagedata: bNrMu9JOI7c6qlgqwD/tC7NVDCO7tujC284UdJZ+MZCNtStoYnKLkdNm7/BzyuseseSIdCajyuxzkl4rmNlCBGIrt4xBkNuT5+scgOjpN5zYFpvGIZx+dWIB8mb9hFM7t9WW2m2egmjVLWIkwOcS4A==
x-ms-exchange-transport-forked: True
Content-Type: multipart/alternative;
	boundary="_000_AM8PR04MB7297FD6E9C6B44728443BDD99B3C9AM8PR04MB7297eurp_"
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-AuthSource: AM7EUR06FT041.eop-eur06.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-Network-Message-Id: 06e50af4-c3bb-44af-e9a1-08d926a736e0
X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Jun 2021 15:49:47.0902
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Internet
X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa
X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM7EUR06HT213
X-OriginatorOrg: outlook.com

Reporting-MTA: dns;AM7EUR06HT213.mail.protection.outlook.com
Received-From-MTA: dns;AM8PR04MB7297.eurprd04.prod.outlook.com
Arrival-Date: Thu, 3 Jun 2021 15:49:47 +0000

Final-Recipient: rfc822;
Action: failed
Status: 5.4.317
Diagnostic-Code: smtp;550 5.4.317 Message expired, cannot connect to remote server
X-Display-Name: =?iso-8859-1?Q?