Replace Zend Mail with PHPMailer (#15891)

* require composer package phpmailer/phpmailer

* change mail class to use phpmailer instead of Zend_Mail

* removes Zend_Mail and Zend_Mime

* submodule

* fix tests

* enable smtp debug for test mail command

* fix embedded images

* set language for phpmailer

* apply some review feedback

* removes Zend_Validate (#15907)

* don't inline file without cid

* submodule update

* fix test

* decouples Mail class from PHPMailer and moves sending mails to new transport layer

* submodule

* cleanup

* unset xmailer header

* simplify mail attachment handling

* adds methods to add bcc recipients

* change implementation of setReplyTo

1 files changed, 77 insertions, 1 deletions

diff --git a/composer.lock b/composer.lock
index aa1d177503..0d7af66819 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "e07cb616b94504f874324c137d7b35f9",
+    "content-hash": "71f3276bfe58917f2a7b5bdd2d993f9a",
     "packages": [
         {
             "name": "composer/ca-bundle",
@@ -1235,6 +1235,82 @@
             "time": "2019-09-26T11:24:58+00:00"
         },
         {
+            "name": "phpmailer/phpmailer",
+            "version": "v6.1.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/PHPMailer/PHPMailer.git",
+                "reference": "a8bf068f64a580302026e484ee29511f661b2ad3"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/PHPMailer/PHPMailer/zipball/a8bf068f64a580302026e484ee29511f661b2ad3",
+                "reference": "a8bf068f64a580302026e484ee29511f661b2ad3",
+                "shasum": ""
+            },
+            "require": {
+                "ext-ctype": "*",
+                "ext-filter": "*",
+                "php": ">=5.5.0"
+            },
+            "require-dev": {
+                "doctrine/annotations": "^1.2",
+                "friendsofphp/php-cs-fixer": "^2.2",
+                "phpunit/phpunit": "^4.8 || ^5.7"
+            },
+            "suggest": {
+                "ext-mbstring": "Needed to send email in multibyte encoding charset",
+                "hayageek/oauth2-yahoo": "Needed for Yahoo XOAUTH2 authentication",
+                "league/oauth2-google": "Needed for Google XOAUTH2 authentication",
+                "psr/log": "For optional PSR-3 debug logging",
+                "stevenmaguire/oauth2-microsoft": "Needed for Microsoft XOAUTH2 authentication",
+                "symfony/polyfill-mbstring": "To support UTF-8 if the Mbstring PHP extension is not enabled (^1.2)"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "PHPMailer\\PHPMailer\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "LGPL-2.1-only"
+            ],
+            "authors": [
+                {
+                    "name": "Marcus Bointon",
+                    "email": "phpmailer@synchromedia.co.uk"
+                },
+                {
+                    "name": "Jim Jagielski",
+                    "email": "jimjag@gmail.com"
+                },
+                {
+                    "name": "Andy Prevost",
+                    "email": "codeworxtech@users.sourceforge.net"
+                },
+                {
+                    "name": "Brent R. Matzelle"
+                }
+            ],
+            "description": "PHPMailer is a full-featured email creation and transfer class for PHP",
+            "funding": [
+                {
+                    "url": "https://marcus.bointon.com/donations/",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/Synchro",
+                    "type": "github"
+                },
+                {
+                    "url": "https://www.patreon.com/marcusbointon",
+                    "type": "patreon"
+                }
+            ],
+            "time": "2020-03-14T14:23:48+00:00"
+        },
+        {
             "name": "piwik/device-detector",
             "version": "3.12.5",
             "source": {