Windows Mail app outgoing mail is suddenly being rejected

Hi

I use the windows Mail app for my hotmail address.

Today outgoing mail has started to be rejected no matter where I send it to (I have tried a non-gmail account too).

Mail sent from the web based version of outlook from the same address arrives as expected.

Any help would be much appreciated

Thanks

Oliver

here is the body of the rejection email (recipient obscured):

Delivery has failed to these recipients or groups:

R***** (*** Email address is removed for privacy ***)
Your message wasn't delivered because the recipient's email provider rejected it.

Diagnostic information for administrators:

Generating server: DB5EUR01HT195.mail.protection.outlook.com

*** Email address is removed for privacy ***
Remote Server returned '550 5.7.520 Message blocked because it contains content identified as spam. AS(4567)'

Original message headers:

Received: from DB5EUR01FT010.eop-EUR01.prod.protection.outlook.com

 (10.152.4.55) by DB5EUR01HT195.eop-EUR01.prod.protection.outlook.com

 (10.152.5.153) with Microsoft SMTP Server (version=TLS1_2,

 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2707.21; Wed, 5 Feb

 2020 11:51:53 +0000

Received: from VI1P193MB0702.EURP193.PROD.OUTLOOK.COM (10.152.4.51) by

 DB5EUR01FT010.mail.protection.outlook.com (10.152.4.136) with Microsoft SMTP

 Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id

 15.20.2686.25 via Frontend Transport; Wed, 5 Feb 2020 11:51:53 +0000

X-IncomingTopHeaderMarker: OriginalChecksum:301F0C8AAAC115D5624933BBF56CDF0AB835F34F977FE009A896DC9C0C81E930;UpperCasedChecksum:A9BF70805DE660A99755E9406232029EF4E8B4EA3CCD5B9E372BD8B775583EF1;SizeAsReceived:6604;Count:42

Received: from VI1P193MB0702.EURP193.PROD.OUTLOOK.COM

 ([fe80::f406:b85f:444:4382]) by VI1P193MB0702.EURP193.PROD.OUTLOOK.COM

 ([fe80::f406:b85f:444:4382%3]) with mapi id 15.20.2707.020; Wed, 5 Feb 2020

 11:51:53 +0000

Content-Type: application/ms-tnef; name="winmail.dat"

Content-Transfer-Encoding: binary

From: O*******e <********.com>

To: ******** <*** Email address is removed for privacy ***>

Subject: test

Thread-Topic: test

Thread-Index: AQHV3BqfaAI0i/XlQ0SJSShJhqJBJQ==

Date: Wed, 5 Feb 2020 11:51:53 +0000

Message-ID: <*** Email address is removed for privacy ***>

Accept-Language: en-GB, en-US

Content-Language: en-GB

X-MS-Has-Attach:

X-MS-TNEF-Correlator: <*** Email address is removed for privacy ***>

MIME-Version: 1.0

X-TMN: [kru5/gt/JYx8oIWY3SrbJcHAN7+uAymn]

X-MS-PublicTrafficType: Email

X-IncomingHeaderCount: 42

Return-Path: *** Email address is removed for privacy ***

X-EOPAttributedMessage: 0

X-MS-Office365-Filtering-Correlation-Id: 32eeb13b-5b6b-490d-900f-08d7aa31cb00

X-MS-TrafficTypeDiagnostic: DB5EUR01HT195: