Decoding Hotmail HTML headers

Hi guys,

I'm trying to decode and understand some content of email headers. I've got a lot of doubts, so I'd appreciate any help.

These are the things I doubt more, and I would like to know its weight regarding deliverability

I don't manage to figure out this headers:

Content-Type:
Sometimes it says boundary=---boundary_etc...... and sometimes says boundary=--=_swift_v4_etc..... what's the difference?

DKIM
I know what DKIM means, but there's a specific label I don't understand. It's the label a inside DKIM. It gives some different options:
* relaxed/relaxed
* simple/simple
* relaxed/simple

What's the difference?

Content-Transfer-Encoding
It says either 7bit or 8bit. Speaking of deliverability, which one suits best?

X-CampaignID:
Is it essential to have it in your emails in order to do have better deliverability?




Here is the code of two emails that give me different information in order to understand what I mean:

EMAIL Nº 1

x-store-info:fHNTDlzCF8Nxw6HwcfGQy53J+UiHye5/BbIMOcvCmV/AccExcduzkDAET4AFwCVxlf7KErsVxCQQGpZE9WJSumOOFBAzp noysa67yQdzNlUOBnHjsyzfTNKUjiNxQM8XlYO0pZKKCC8CC7a G+jrpFQ==
Authentication-Results: hotmail.com; spf=pass (sender IP is 31.24.40.204) smtp.mailfrom=news@boletin.tipo.es; dkim=pass header.d=boletin.tipo.es; x-hmca=pass header.id=news@boletin.tipo.es
X-SID-PRA: news@boletin.tipo.es
X-AUTH-Result: PASS
X-SID-Result: PASS
X-Message-Status: n:n
X-Message-Delivery: Vj0xLjE7dXM9MDtsPTE7YT0wO0Q9MjtHRD0yO1NDTD00
X-Message-Info: 11chDOWqoTmLuCCnFcMKbiUazw2QCxXmbG6o4mCmscv+V5e0Td HHQV2mT/j71/06YOMaaByq2na3Fq4Z2iKJqWkS/KogYzLyvE7V6FoyNZ7N7fyGiWbKH4cG570Yc2JMFbBRibFNcob J+U0XwefxDgduZ/P43ADA0xqPoLpyYhv9a6dInI+f9ynyHOjA7Fg1Bg8/L97wFK3WueKKawzX2lSILYT9nu3SttlzG8YkJCE=
Received: from mailsrv214.abseli.net ([31.24.40.204]) by SNT004-MC2F24.hotmail.com with Microsoft SMTPSVC(7.5.7601.23143);
Tue, 25 Aug 2015 05:49:20 -0700
Received: from mailsrv214.abseli.net (mailsrv214.abseli.net [31.24.40.204])
by mailsrv214.abseli.net (Postfix) with ESMTP id 64E1F251826C
for <raulambeminem@hotmail.com>; Tue, 25 Aug 2015 14:49:20 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=boletin.tipo.es;
s=sign31; t=1440506960;
bh=H6Drvy5FL8awIO6rFt/VUUnGBE4o3c4smaug8MJTobE=;
h=Message-IDate:Subject:From:To:MIME-Version:Content-Type;
b=nZ0QVUxod5VAvOjmmSQpsvNOwgEt5975i+lomb+eh+vr5DXg LVYF8kvXIomw+O2as
OL6njVLCsdJOT7LiAlhe/JEiNoZOjpau3SGhwatM+ffp0UNuwkGc6ODN3LZgKjeMzD
pH3Z3y1sMl2FQvjS6BWWveC8Eti3o93o6HTi9drE=
Message-ID: <1440506960.55dc64505f589@mailsrv214.abseli.net>
Date: Tue, 25 Aug 2015 14:49:20 +0200
Subject: =?utf-8?Q?=E2=97=86_Ll=C3=A9vate?= de regalo nuestra mochila al
hacer tu compra: =?utf-8?Q?=C2=A1Date?= prisa quedan pocos
=?utf-8?Q?d=C3=ADas!_=E2=97=86?=
From: Tiendas Tipo <news@boletin.tipo.es>
To: raulambeminem@hotmail.com
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="_=_swift_v4_144050696055dc6450614cf_=_"
X-MimeOLE: Produced By CampaignSG V6
X-CampaignID: OnJhdWxhbWJlbWluZW1AaG90bWFpbC5jb20=
Return-Path: news@boletin.tipo.es
X-OriginalArrivalTime: 25 Aug 2015 12:49:21.0263 (UTC) FILETIME=[76783FF0:01D0DF34]


--_=_swift_v4_144050696055dc6450614cf_=_
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit



EMAIL Nº 2
x-store-info:w5JOV+GpEg16Hd3Liu8PdV6w7ot2s5vN
Authentication-Results: hotmail.com; spf=pass (sender IP is 217.113.251.237) smtp.mailfrom=info@infor.calidadbarata.es; dkim=permerror header.d=calidadbarata.es; x-hmca=pass header.id=info@infor.calidadbarata.es
X-SID-PRA: info@infor.calidadbarata.es
X-AUTH-Result: PASS
X-SID-Result: PASS
X-Message-Status: n:n
X-Message-Delivery: Vj0xLjE7dXM9MDtsPTA7YT0xO0Q9MjtHRD0xO1NDTD0w
X-Message-Info: /3z5fcrqMMVgdSeliANhf/LuqUPMGNWbwEYCasqlzqpcX6cFtdu2XJFrXIsNFHWLbHn7OKkd DvQDJ7R50m6R9fex5Lcsjl17D/8k0Nw/9fF3OeGLtLgiE2OL07dOWReGqB51yVEhMmvkH56dzDW+hnrG8q sH/rS9h6RlzxAZaeEzLbVaLQaFUVKvgOblbuYmomgYDqcIXsDFl1i mRx5ShL+t8tj/blGMO2Y1tBcJ3F2oOBK70dl/6g==
Received: from servicios9.progress-event.eu ([217.113.251.237]) by BAY004-MC6F19.hotmail.com with Microsoft SMTPSVC(7.5.7601.23143);
Mon, 31 Aug 2015 02:32:40 -0700
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; s=key1; d=calidadbarata.es;
h=MIME-Version:From:Toate:Subject:Content-Type:Message-ID; i=info@infor.calidadbarata.es;
bh=Ul7iKh0r8O44OrVduPOzL/NfYDY=;
b=fFfPSWarnSkRhsctTVeYt5//Ip4CDpI43iJh7ofRzKpfVujiSOVZfz+wEnbAQ6veIM+FQHJC3Z 9d
PgQXq/gLBPRDRSQZkNJ3llxRD2c9h9Hfx+uGD1hpm7KVjKM2uolaVej1 3XSHRktJwFBtQsNV8eXi
Dyt5F1wgBgRpFmGhCF8=
MIME-Version: 1.0
From: "Pedido" <info@infor.calidadbarata.es>
To: calentamientoar25@hotmail.com
Date: 31 Aug 2015 11:32:38 +0200
Subject: =?utf-8?B?IEJpZW52ZW5pZG8vYTogbWlsZXMgYmVuZWZpY2lvcyBmYW N0?=
=?utf-8?B?dXJhLi4uIMKhcGVkaWRvIGluZm9ybWFjacOzbiHigI8=?=
Content-Type: multipart/alternative;
boundary=--boundary_1396_0c48af8e-1e88-44e7-b1bb-75fe830f69ff
Message-ID: <0.0.0.2F.1D0E3E15BE64428.0@servicios9.progress-event.eu>
Return-Path: info@infor.calidadbarata.es
X-OriginalArrivalTime: 31 Aug 2015 09:32:40.0862 (UTC) FILETIME=[FB5C73E0:01D0E3CF]


----boundary_1396_0c48af8e-1e88-44e7-b1bb-75fe830f69ff
Content-Type: text/plain
Content-Transfer-Encoding: 7bit


Thanks beforehand