I'll be honest here, I'm not sure what's caused this. Research on the Web reveals some issues with an Outlook plugin last April, which caused similar issues for some. I believe this to be either an Outlook issue or a device problem, though am happy to be corrected if wrong.
A little out of my depth on this as nothing amiss our side. Would like for the Community to offer advice on this.
Received: from VI1PR08MB0861.eurprd08.prod.outlook.com (10.152.12.55) by VE1EUR02FT025.mail.protection.outlook.com (10.152.12.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1580.10 via Frontend Transport; Thu, 31 Jan 2019 19:46:11 +0000 Received: from VI1PR08MB0861.eurprd08.prod.outlook.com ([fe80::c15e:af69:7675:8e91]) by VI1PR08MB0861.eurprd08.prod.outlook.com ([fe80::c15e:af69:7675:8e91%2]) with mapi id 15.20.1558.023; Thu, 31 Jan 2019 19:46:11 +0000
To be frank this is why I like to see ALL the headers (minus full email address) in an email like this. They often tell a bigger picture.
MAPI is Microsofts Messaging API and is a Microsoft specific protocol used on Exchange servers. (Although Unix does have something that emulates MAPI)
It's odd because the fe80 numbers are Link Local IPv6 addresses (in fact they're identical apart from the %2 which is an interface identifier) and shows the Server sending the message to itself and then sending the message to what appears to be one of Microsoft Mail Exchangers (inbound mail servers).
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