For some reason, emails from senders who send an email via outlook (Microsoft SMTP Server) are always delayed. I have attached part of email header below which states that email was sent on "Fri, 22 Dec 2017 12:04:07" and received by recipient on "24 Dec 2017 09:35:51". I am trying to figure out if this is something to do with recipients' server.
Received: (qmail 13360 invoked from network); 24 Dec 2017 09:35:51 +0000
Received-SPF: pass (mail.recipient.com: domain of sender.com designates 1.4.0.7 as permitted sender) client-ip=1.4.0.7; envelope-from=joe.doe@sender.com; helo=EUR01-HE1-obe.outbound.protection.outlook.com;
Received: from mail-h.outbound.protection.outlook.com (HELO EUR01-HE1-obe.outbound.protection.outlook.com) (1.4.0.7)
by mail.recipient.com with (AES256-SHA256 encrypted) SMTP; 24 Dec 2017 09:35:50 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sender.com;
s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version;
bh=ISi0L6tR9zqfsnFftiji3pKtbhiZLMV1OvzrGTnAMGc=;
b=Rv07QHqSDhDJw2pmt3T+NRCXMRHGuFR8qzu8/HVvNWD8sCvliOdO7GEYEkXFe6e3Y6r7cFGtmIV4o9LWLmofiBwbxXmdluGuKE1aAp9gUg93DCSVcHKmb/rvuVjY4R6/6LpO9xzW5cbfe3sw11oIIgrXWFwD9CGlGjxZTdtb0c4=
Received: from D.eurprd07.prod.outlook.com (2603:10a6:4:4f::22)
by D.eurprd07.prod.outlook.com (2603:10a6:4:4f::22) with
TransportReplication id Version 15.20 (Build 366.3); Sat, 23 Dec 2017
09:01:54 +0000
Received: from A.eurprd07.prod.outlook.com (2603)
by V.eurprd07.prod.outlook.com (26030) with
Microsoft SMTP Server (version=TLS1_2,
cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 1.2.3.1; Fri, 22
Dec 2017 12:04:11 +0000
Received: from V.eop-EUR03.prod.protection.outlook.com
(2a01) by A.outlook.office365.com
(2603) with Microsoft SMTP Server (version=TLS1_2,
cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 1.2.3.3 via Frontend
Transport; Fri, 22 Dec 2017 12:04:11 +0000
Authentication-Results: spf=pass (sender IP is 6.2.6.1)
smtp.mailfrom=sender.com; recipient.com; dkim=none (message not
signed) header.d=none;recipient.com; dmarc=pass action=none
header.from=sender.com;
Received-SPF: Pass (protection.outlook.com: domain of sender.com designates
6.2.6.1 as permitted sender) receiver=protection.outlook.com;
client-ip=6.2.6.1; helo=sender.com;
Received: from sender.com (6.2.6.1) by
V.mail.protection.outlook.com (1.1.1.6) with Microsoft SMTP
Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id
1.2.3.6 via Frontend Transport; Fri, 22 Dec 2017 12:04:10 +0000
Received: from ODCFRAEX14.domain.local (192.168.1.1) by
ODCFRAEX14.domain.local (192.168.1.1) with Microsoft SMTP Server
(TLS) id 15.0.1347.2; Fri, 22 Dec 2017 13:04:07 +0100
Received: from ODCFRAEX14.domain.local ([fe80]) by
ODCFRAEX14.domain.local ([fe80]) with mapi id
15.00.1347.000; Fri, 22 Dec 2017 13:04:07 +0100
Date: Fri, 22 Dec 2017 12:04:07 +0000
