Category Archives: SMTP

simple question about smtp server ( msa to mta ) security design?

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Not sure if this is due to security; hence the reason i am asking here.
I have 2 SMTP server and a couple of unix servers

  1. the actual mailserver running on window. client connect to it and download mail.
  2. a postfix SMTP server running in one of the unix box use for relaying mail to 1).

We call my mailserver MTA1 and the POSTFIX server MTA2

I am a novice in mail and i realize these following different flows when some of the different unix servers are sending mail to the public

They can either

  1. unix server (mailx) –> (localhost-sendmail) —> MTA2(postfix) –>
    MTA1 (actual mailserver) –> external MTA

  2. unix server (mailx) –> MTA2(postfix) –> MTA1 (actual mailserver) –> external MTA

  3. unix server (mailx) –> MTA2(postfix) –> external recipient MTA

  4. unix server (mailx) –> MTA1 –> external recipient MTA

  5. unix server (mailx) —> (localhost-sendmail) –> external recipient MTA directly ?

q1) Is all the above paths valid ? If so, what should be the correct way ?

q1) Notice 1), not sure why there is a sendmail listening on localhost when the MUA can go directly to MTA2 or MTA1 (like path2)

q2) Notice 2) not sure why the need for MTA2 to relay to MTA1 when they can go the 3) path

q3) Notice 3) not sure why the need to go to MTA2 when they can go to MTA1 also

q4) Notice 5) i have a strong feeling i can send to the sendmail on localhost and have it send to the external MTA directly.

So which is the right path ?

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Sen. Wyden calls out Pentagon for not adopting email encryption technology

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Sen. Ron Wyden, D-Ore., wants to know why the Defense Information Systems Agency has failed to implement a basic encryption technology that would otherwise protect employees’ emails from being intercepted by hackers and foreign intelligence agencies, according to a recent letter written sent to DISA Director Lt. Gen. Alan Lynn. Wyden is requesting information concerning why DISA has lagged behind the vast majority of U.S. intelligence agencies, including the CIA and NSA, in adopting a widely used encryption technology known as STARTTLS to protect unclassified email systems. STARTTLS adds a layer of web encryption over the email protocol SMTP. DISA is responsible for providing email services to the Coast Guard, Army, Navy and Marines. An agency spokesperson confirmed that DISA received Wyden’s letter. While the technology is far from a cure-all against hackers that seek to spy on a target, the technology can help ensure the confidentiality of emails that […]

The post Sen. Wyden calls out Pentagon for not adopting email encryption technology appeared first on Cyberscoop.

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Sen. Wyden calls out Pentagon for not adopting email encryption technology

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Sen. Ron Wyden, D-Ore., wants to know why the Defense Information Systems Agency has failed to implement a basic encryption technology that would otherwise protect employees’ emails from being intercepted by hackers and foreign intelligence agencies, according to a recent letter written sent to DISA Director Lt. Gen. Alan Lynn. Wyden is requesting information concerning why DISA has lagged behind the vast majority of U.S. intelligence agencies, including the CIA and NSA, in adopting a widely used encryption technology known as STARTTLS to protect unclassified email systems. STARTTLS adds a layer of web encryption over the email protocol SMTP. DISA is responsible for providing email services to the Coast Guard, Army, Navy and Marines. An agency spokesperson confirmed that DISA received Wyden’s letter. While the technology is far from a cure-all against hackers that seek to spy on a target, the technology can help ensure the confidentiality of emails that […]

The post Sen. Wyden calls out Pentagon for not adopting email encryption technology appeared first on Cyberscoop.

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Fake Failed Delivery from Congress? [on hold]

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I was hoping someone could help. I recently emailed the staff of my local U.S. Representative, but then got back a very fishy looking failed delivery response. It looks like this is an auto-reply set up in an Exchange client or server that’s meant to deceive people that their message bounced. But I don’t have the expertise to say this is the case. Is this real or no? The message is below and names and IPs have been redacted.

Can anyone comment on this?

Delivered-To: XXX@gmail.com
Received: by XXX with SMTP id 21csp688769qtu;
        Thu, 16 Mar 2017 05:52:12 -0700 (PDT)
X-Received: by XXX with SMTP id z185mr7550566qka.281.1489668732321;
        Thu, 16 Mar 2017 05:52:12 -0700 (PDT)
Return-Path: <>
Received: from s-hub4.house.gov (s-hub4.house.gov. [XXX])
        by mx.google.com with ESMTPS id a49si3808247qta.XXX
        for <XXX>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Thu, 16 Mar 2017 05:52:12 -0700 (PDT)
Received-SPF: pass (google.com: domain of postmaster@s-hub4.house.gov designates XXX as permitted sender) client-ip=XXX;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@mail.house.gov;
       spf=pass (google.com: domain of postmaster@s-hub4.house.gov designates XXX as permitted sender) smtp.helo=s-hub4.house.gov;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=house.gov
Received: from HEOC-HT02.US.House.gov (heoc-ht02.us.house.gov [XXX])
    by s-hub4.house.gov  with ESMTP id v2GCqBns015996
    (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256 bits) verified FAIL)
    for <XXX>; Thu, 16 Mar 2017 08:52:11 -0400
X-DKIM: OpenDKIM Filter v2.4.3 s-hub4.house.gov v2GCqBns015996
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.house.gov;
    s=November2012-msg-mhg; t=1489668731;
    bh=TmgnphVFgTCKIaXsHTOpfMwuIrvFX1GE2ZdHrvyH69E=;
    h=From:To:Subject:Date:Message-ID:References:In-Reply-To:
     Content-Type:MIME-Version;
    b=lZFhl9Re75ZlwzkPlBmLuqiMoKyeWrXuOJ3grkNR8/GDPTg0c2afcY/JfrOzJKttd
     hehMBaflMTtE+FqmvXX2h/t1IAZaK41t0nTVeNMqwa5iQ47NoxyI0wa9pikF1FCI0R
     SAoFXlOijWSTB4aCRWS4ig50IKSEl5du22vZRrCg=
Received: from HEOC-HT02.US.House.gov ([::1]) by HEOC-HT02.US.House.gov
 ([::1]) with Microsoft SMTP Server id XXX; Thu, 16 Mar 2017
 08:52:11 -0400
From: “XXX” <XXX@mail.house.gov>
To: XXX <XXX>
Subject: Automatic reply: Time to talk?
Thread-Topic: Time to talk?
Thread-Index: AQHSnlQhPY8xyUcU80mmEIbCQOp84Q==
Date: Thu, 16 Mar 2017 12:52:11 +0000
Message-ID: <e1494dbd073849049ac019fb2f88ccee@HEOC-HT02.US.House.gov>
References: <CAJNUnm93=be67AEat+z34P5VtLDLA3QOugpZt1+-gCLhmprNvA@mail.gmail.com>
In-Reply-To: <CAJNUnm93=be67AEat+z34P5VtLDLA3QOugpZt1+-gCLhmprNvA@mail.gmail.com>
X-MS-Has-Attach:
X-Auto-Response-Suppress: All
X-MS-Exchange-Inbox-Rules-Loop: XXX@mail.house.gov
X-MS-TNEF-Correlator:
Content-Type: multipart/alternative;
    boundary="_000_e1494dbd073849049ac019fb2f88cceeHEOCHT02USHousegov_"
MIME-Version: 1.0

--_000_e1494dbd073849049ac019fb2f88cceeHEOCHT02USHousegov_
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

A message that you sent could not be delivered to one or more of its recipi=
ents. The following address(es) failed:


[XXX@mail.house.gov<mailto:XXX@mail.house.gov>]

--_000_e1494dbd073849049ac019fb2f88cceeHEOCHT02USHousegov_
Content-Type: text/html; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/htm=
l4/strict.dtd">
<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dus-ascii"=
>
<meta http-equiv=3D"Content-Style-Type" content=3D"text/css">
<title></title>
<meta name=3D"Generator" content=3D"Cocoa HTML Writer">
<meta name=3D"CocoaVersion" content=3D"1404.34">
<style type=3D"text/css">=0A=
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; line-height: 18.0px; font: 15.0px Ca=
libri; -webkit-text-stroke: #000000}=0A=
p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; line-height: 18.0px; font: 15.0px Ca=
libri; -webkit-text-stroke: #000000; min-height: 18.0px}=0A=
span.s1 {font-kerning: none}=0A=
</style>
</head>
<body>
<p class=3D"p1"><span class=3D"s1">A message that you sent could not be del=
ivered to one or more of its recipients. The following address(es) failed:<=
/span></p>
<p class=3D"p2"><span class=3D"s1"></span><br>
</p>
<p class=3D"p1"><span class=3D"s1">[<a href=3D"mailto:XXX@mail.hou=
se.gov">XXX@mail.house.gov</a>]</span></p>
</body>
</html>

--_000_e1494dbd073849049ac019fb2f88cceeHEOCHT02USHousegov_--

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