diff --git a/composer.json b/composer.json
index 95b404852..64e353bdf 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
         "ext-pdo_sqlite": "*",
         "ext-mbstring": "*",
         "dimsemenov/magnific-popup": "~1.0",
-        "phpmailer/phpmailer": "~5.2",
+        "phpmailer/phpmailer": "~6.5",
         "twbs/bootstrap": "~3.3",
         "bower-asset/jquery": "~1.12",
         "bower-asset/jquery-cookie": "~1.4",
diff --git a/composer.lock b/composer.lock
index 6d7ecc224..171c0ce86 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": "4575b543f8d75643029b3031ddcfc504",
+    "content-hash": "ba64a06696e05047bc95888a6f8ba39e",
     "packages": [
         {
             "name": "bower-asset/dot",
@@ -140,70 +140,59 @@
         },
         {
             "name": "phpmailer/phpmailer",
-            "version": "v5.2.27",
+            "version": "v6.5.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHPMailer/PHPMailer.git",
-                "reference": "dde1db116511aa4956389d75546c5be4c2beb2a6"
+                "reference": "a5b5c43e50b7fba655f793ad27303cd74c57363c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHPMailer/PHPMailer/zipball/dde1db116511aa4956389d75546c5be4c2beb2a6",
-                "reference": "dde1db116511aa4956389d75546c5be4c2beb2a6",
+                "url": "https://api.github.com/repos/PHPMailer/PHPMailer/zipball/a5b5c43e50b7fba655f793ad27303cd74c57363c",
+                "reference": "a5b5c43e50b7fba655f793ad27303cd74c57363c",
                 "shasum": ""
             },
             "require": {
                 "ext-ctype": "*",
-                "php": ">=5.0.0"
+                "ext-filter": "*",
+                "ext-hash": "*",
+                "php": ">=5.5.0"
             },
             "require-dev": {
-                "doctrine/annotations": "1.2.*",
-                "jms/serializer": "0.16.*",
-                "phpdocumentor/phpdocumentor": "2.*",
-                "phpunit/phpunit": "4.8.*",
-                "symfony/debug": "2.8.*",
-                "symfony/filesystem": "2.8.*",
-                "symfony/translation": "2.8.*",
-                "symfony/yaml": "2.8.*",
-                "zendframework/zend-cache": "2.5.1",
-                "zendframework/zend-config": "2.5.1",
-                "zendframework/zend-eventmanager": "2.5.1",
-                "zendframework/zend-filter": "2.5.1",
-                "zendframework/zend-i18n": "2.5.1",
-                "zendframework/zend-json": "2.5.1",
-                "zendframework/zend-math": "2.5.1",
-                "zendframework/zend-serializer": "2.5.*",
-                "zendframework/zend-servicemanager": "2.5.*",
-                "zendframework/zend-stdlib": "2.5.1"
+                "dealerdirect/phpcodesniffer-composer-installer": "^0.7.0",
+                "doctrine/annotations": "^1.2",
+                "phpcompatibility/php-compatibility": "^9.3.5",
+                "roave/security-advisories": "dev-latest",
+                "squizlabs/php_codesniffer": "^3.5.6",
+                "yoast/phpunit-polyfills": "^0.2.0"
             },
             "suggest": {
-                "league/oauth2-google": "Needed for Google XOAUTH2 authentication"
+                "ext-mbstring": "Needed to send email in multibyte encoding charset or decode encoded addresses",
+                "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": {
-                "classmap": [
-                    "class.phpmailer.php",
-                    "class.phpmaileroauth.php",
-                    "class.phpmaileroauthgoogle.php",
-                    "class.smtp.php",
-                    "class.pop3.php",
-                    "extras/EasyPeasyICS.php",
-                    "extras/ntlm_sasl_client.php"
-                ]
+                "psr-4": {
+                    "PHPMailer\\PHPMailer\\": "src/"
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
-                "LGPL-2.1"
+                "LGPL-2.1-only"
             ],
             "authors": [
-                {
-                    "name": "Jim Jagielski",
-                    "email": "jimjag@gmail.com"
-                },
                 {
                     "name": "Marcus Bointon",
                     "email": "phpmailer@synchromedia.co.uk"
                 },
+                {
+                    "name": "Jim Jagielski",
+                    "email": "jimjag@gmail.com"
+                },
                 {
                     "name": "Andy Prevost",
                     "email": "codeworxtech@users.sourceforge.net"
@@ -213,7 +202,17 @@
                 }
             ],
             "description": "PHPMailer is a full-featured email creation and transfer class for PHP",
-            "time": "2018-11-15T22:32:31+00:00"
+            "support": {
+                "issues": "https://github.com/PHPMailer/PHPMailer/issues",
+                "source": "https://github.com/PHPMailer/PHPMailer/tree/v6.5.0"
+            },
+            "funding": [
+                {
+                    "url": "https://github.com/Synchro",
+                    "type": "github"
+                }
+            ],
+            "time": "2021-06-16T14:33:43+00:00"
         },
         {
             "name": "rsms/js-lru",
@@ -2623,5 +2622,6 @@
     "platform-dev": [],
     "platform-overrides": {
         "php": "5.6"
-    }
+    },
+    "plugin-api-version": "2.1.0"
 }