Hopefully that is the end of it.
Forgive me if this is stuff you already know, I don't know your technical level however the senders email address can be spoofed. It is actually quite easy to do. Literally I can spoof any email address to look like it came from a specific sender. As the recipient it is up to your email security to determine if the source is legit and apply whatever scrutiny and rules as it moves through your mail service.
One thing I do beyond upstream mail filtering and security is I view all email in pain text. It does not look sexy but if I trust the source I can always flip the view to HTML or in the case of Outlook HTML or RTF and see it how it was intended. Viewing email in plain text has the benefit that it breaks down the email into it's three basic constituents, the header, the body and attachments. This benefits your security by pulling out the embedded objects and converting them as attachments, URLs can be clearly viewed and any embedded code that can otherwise self execute becomes ineffective.
The rest of this is somewhat technical but for anyone interested below is a look under the hood of a typical email.
The header is what contains most of the diagnostic information beyond what is visible, the sender, recipients, subject, date etc. Below is a non-parsed example of an email header taken from a recent email I received using Outlook 2011 as the email client, and I use Exchange 2013 as the recipient server. I have made some minor changes to it for security reasons. As the email moves from the sender to the recipient, it moves from system to system and these systems append this header including time stamps. This allows administrators to diagnose many issues including security issues.
Received: from S05-MBX04-22.S05.local (10.30.33.126) by S05-MBX04-17.S05.local
(10.30.33.104) with Microsoft SMTP Server (TLS) id 15.0.1347.2 via Mailbox
Transport; Mon, 25 Dec 2017 03:59:06 -0500
Received: from S05-CAS014.S05.local (10.30.33.51) by S05-MBX04-22.S05.local
(10.30.33.126) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 25 Dec
2017 03:59:05 -0500
Received: from S05-MFBE11-15.S05.local (10.30.33.225) by S05-CAS014.S05.local
(10.30.33.51) with Microsoft SMTP Server id 15.0.1347.2 via Frontend
Transport; Mon, 25 Dec 2017 03:59:05 -0500
Received: from S05-MFFE11.S05.local (mailfilter5-1.sherwebcloud.com [199.244.76.190])
by S05-MFBE11-15.S05.local (Postfix) with ESMTP id E151820000DB
for <
[email protected]>; Mon, 25 Dec 2017 03:59:03 -0500 (EST)
Received: from mail-qk0-f177.google.com (mail-qk0-f177.google.com [209.85.220.177])
by mx05-1.mycloudmailbox.com (Postfix) with ESMTPS id D0AC820000CF
for <
[email protected]>; Mon, 25 Dec 2017 03:59:03 -0500 (EST)
Received: by mail-qk0-f177.google.com with SMTP id g123so9104741qka.3
for <
[email protected]>; Mon, 25 Dec 2017 00:59:03 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=gmail.com; s=20161025;
h=mime-version:in-reply-to:references:from:date:message-id:subject:to
:cc;
bh=bqE+kJpYB7PtarT8Y3IZvobgNa9qVGv8lFbEgKhSbxY=;
b=eXfXJLIlMt3iwq9AbZUuyVQlE0NJVXzW4H63pIhbZ6HYhcgJ13tE9yruDnDZz0/nXD
uytKOQ4fZeOwM6dZ2a1euJDvEb/oDD3dmW7Q9hxkeZXrskbU9P3fEG9yTQvSXZOEcTZn
FPtsfOOQ2oLBHniC7t0gUQj1F7vUkOgBUH5T6Vd1UlVw1TmMkUoX7BMVevL2e9meo0Hc
QChwEx/i9rBAkZ1ODMl1YHgedjbLnMJvswl0U4XrlO4xhJPFc0JKAy9ht10997SxBjeb
a8YKLDbNSa0iC2UwQh8QTm3+r0RKH/9PkkDo4Y/pDts3T+5BoiMTfrSOvAfESxnU9RFH
6J2w==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20161025;
h=x-gm-message-state:mime-version:in-reply-to:references:from:date
:message-id:subject:to:cc;
bh=bqE+kJpYB7PtarT8Y3IZvobgNa9qVGv8lFbEgKhSbxY=;
b=ZAhLI8iWHnpkx8GhKcL3vgPVZiqXIT5PcuZf+jEJcUFONJ8HdRSU8smaUxTcDys+ZD
6jDIthtkc+jmfPJ4dp4Y6y+URGynFWJDE0vjGEdy8cHTVZ/iuFs4cDl33TNTDbmTpm1j
vkzwRpPXMoZ7iJlJCux2D/P2tqMr2e1Jk7xw1TxwHGx91ERdu/mHoAs/iC1aDui8VsQZ
A+D/yIm5Qblmjjt3oPCuFhoKvTadoIwBpyfil0PdevslHrmwSoZI/h3tog3bdULdakoW
gQ6l4zfiVyKRtEMoQ2QnCj7cEZw/Ls6I2tpgM7fQA/zmch/MpwWwTl/dQi6Phe7aFpSL
bt/Q==
X-Gm-Message-State: AKGB3mLqWCCGiv66b3YUODhA+kU8uaBWCdXc9/3sZwX+bqu3EWfseGC5
YiKHMkDsIfdB/qPElTHg+/0jMNdX5B55EwdsQ4vz0w==
X-Google-Smtp-Source: ACJfBouFJ/7/o1WB7JlvIHGxjq8jTASosjoJ0strA3JOm+m8FFWax9spjEvsFkn57HQEmajmEYmibgmf91S7YqLOFUc=
X-Received: by 10.55.181.66 with SMTP id e63mr29155343qkf.130.1514192343065;
Mon, 25 Dec 2017 00:59:03 -0800 (PST)
MIME-Version: 1.0
Received: by 10.140.96.139 with HTTP; Mon, 25 Dec 2017 00:58:42 -0800 (PST)
In-Reply-To: <
[email protected]>
References: <
[email protected]>
From: Aqua Sense <
[email protected]>
Date: Mon, 25 Dec 2017 03:58:42 -0500
Message-ID: <CAJrj7
[email protected]>
Subject: Re: New message on AquaSenseW.com
To:
[email protected]
Cc: David Green <
[email protected]>
X-MF-Information: Contact support for more information
X-MF-ID: E151820000DB.A6970
X-MF-MailCheck: Not scanned
X-MF-IP-Protocol: IPv4
X-MF-SpamCheck: not spam, SpamAssassin (not cached, score=0.63, required 5,
autolearn=disabled, DCC_REPUT_13_19 -0.10, FREEMAIL_FROM 0.25,
HTML_MESSAGE 0.50, RCVD_IN_DNSWL_NONE -0.00, RCVD_IN_MSPIKE_H3 -0.01,
RCVD_IN_MSPIKE_WL -0.01)
X-MF-From:
[email protected]
X-Spam-Status: No
Return-Path:
[email protected]
X-MS-Exchange-Organization-Network-Message-Id: 34390ab6-e469-4cd3-554c-08d54b75c0b5
X-RoutingAgent: Treated
X-MS-Exchange-Organization-AuthSource: S05-CAS014.S05.local
X-MS-Exchange-Organization-AuthAs: Anonymous
Content-type: multipart/alternative;
boundary="B_3597425005_1475338"
> This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
--B_3597425005_1475338
Content-type: text/plain;
charset="UTF-8"
Content-transfer-encoding: quoted-printable
Hello Michael
=E2=80=8BCan you give us a approximate size for your project? And what can we help
you with? We are freshwater only aquarium store but my colleagues have good
experience with saltwater aquariums
--B_3597425005_1475338
Content-type: text/html;
charset="UTF-8"
Content-transfer-encoding: quoted-printable
<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dutf-8">
</head>
<body>
<div dir=3D"ltr">
<div class=3D"gmail_default" style=3D"color:rgb(68,68,68)">Hello Michael</div>
<div class=3D"gmail_default" style=3D"color:rgb(68,68,68)"><br>
</div>
<div class=3D"gmail_default" style=3D"color:rgb(68,68,68);display:inline">=E2=80=8BCa=
n you give us a approximate size for your project? And what can we help you =
with? We are freshwater only aquarium store but my colleagues have good expe=
rience with saltwater aquariums</div>
</div>
</body>
</html>
--B_3597425005_1475338--
Using an email header analyzer, in this case from mxtoolbox.com, you can parse and brake it down into a more readable format:
Header Name | Header Value |
---|
DKIM-Signature | v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=bqE+kJpYB7PtarT8Y3IZvobgNa9qVGv8lFbEgKhSbxY=; b=eXfXJLIlMt3iwq9AbZUuyVQlE0NJVXzW4H63pIhbZ6HYhcgJ13tE9yruDnDZz0/nXD uytKOQ4fZeOwM6dZ2a1euJDvEb/oDD3dmW7Q9hxkeZXrskbU9P3fEG9yTQvSXZOEcTZn FPtsfOOQ2oLBHniC7t0gUQj1F7vUkOgBUH5T6Vd1UlVw1TmMkUoX7BMVevL2e9meo0Hc QChwEx/i9rBAkZ1ODMl1YHgedjbLnMJvswl0U4XrlO4xhJPFc0JKAy9ht10997SxBjeb a8YKLDbNSa0iC2UwQh8QTm3+r0RKH/9PkkDo4Y/pDts3T+5BoiMTfrSOvAfESxnU9RFH 6J2w== |
X-Google-DKIM-Signature | v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=bqE+kJpYB7PtarT8Y3IZvobgNa9qVGv8lFbEgKhSbxY=; b=ZAhLI8iWHnpkx8GhKcL3vgPVZiqXIT5PcuZf+jEJcUFONJ8HdRSU8smaUxTcDys+ZD 6jDIthtkc+jmfPJ4dp4Y6y+URGynFWJDE0vjGEdy8cHTVZ/iuFs4cDl33TNTDbmTpm1j vkzwRpPXMoZ7iJlJCux2D/P2tqMr2e1Jk7xw1TxwHGx91ERdu/mHoAs/iC1aDui8VsQZ A+D/yIm5Qblmjjt3oPCuFhoKvTadoIwBpyfil0PdevslHrmwSoZI/h3tog3bdULdakoW gQ6l4zfiVyKRtEMoQ2QnCj7cEZw/Ls6I2tpgM7fQA/zmch/MpwWwTl/dQi6Phe7aFpSL bt/Q== |
X-Gm-Message-State | AKGB3mLqWCCGiv66b3YUODhA+kU8uaBWCdXc9/3sZwX+bqu3EWfseGC5 YiKHMkDsIfdB/qPElTHg+/0jMNdX5B55EwdsQ4vz0w== |
X-Google-Smtp-Source | ACJfBouFJ/7/o1WB7JlvIHGxjq8jTASosjoJ0strA3JOm+m8FFWax9spjEvsFkn57HQEmajmEYmibgmf91S7YqLOFUc= |
X-Received | by 10.55.181.66 with SMTP id e63mr29155343qkf.130.1514192343065; Mon, 25 Dec 2017 00:59:03 -0800 (PST) |
MIME-Version | 1.0 |
In-Reply-To | <[email protected]> |
References | <[email protected]> |
From | Aqua Sense <[email protected]> |
Date | Mon, 25 Dec 2017 03:58:42 -0500 |
Message-ID | <CAJrj7[email protected]> |
Subject | Re: New message on AquaSenseW.com |
To | [email protected] |
Cc | David Green <[email protected]> |
X-MF-Information | Contact support for more information |
X-MF-ID | E151820000DB.A6970 |
X-MF-MailCheck | Not scanned |
X-MF-IP-Protocol | IPv4 |
X-MF-SpamCheck | not spam, SpamAssassin (not cached, score=0.63, required 5, autolearn=disabled, DCC_REPUT_13_19 -0.10, FREEMAIL_FROM 0.25, HTML_MESSAGE 0.50, RCVD_IN_DNSWL_NONE -0.00, RCVD_IN_MSPIKE_H3 -0.01, RCVD_IN_MSPIKE_WL -0.01) |
X-MF-From | [email protected] |
X-Spam-Status | No |
Return-Path | [email protected] |
X-MS-Exchange-Organization-Network-Message-Id | 34390ab6-e469-4cd3-554c-08d54b75c0b5 |
X-RoutingAgent | Treated |
X-MS-Exchange-Organization-AuthSource | S05-CAS014.S05.local |
X-MS-Exchange-Organization-AuthAs | Anonymous |
(1) Content 1 type text/plain | Hello Michael=E2=80=8BCan you give us a approximate size for your project? And what can we help you with? We are freshwater only aquarium store but my colleagues have good experience with saltwater aquariums |