diff --git a/api/admin/ticket/index.php b/api/admin/ticket/index.php
index f347af43..0875e908 100644
--- a/api/admin/ticket/index.php
+++ b/api/admin/ticket/index.php
@@ -32,7 +32,7 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiSuccess {Integer} priority The ID of the priority the ticket is in
  * @apiSuccess {String} subject The subject of the ticket
  * @apiSuccess {String} message The original message of the ticket
- * @apiSuccess {String} dateCreated The date and time the ticket was submitted, in `YYYY-MM-DD hh:mm:ss`
+ * @apiSuccess {Date} dateCreated The date and time the ticket was submitted
  * @apiSuccess {Integer} articles The knowledgebase article IDs suggested when the user created the ticket
  * @apiSuccess {String} ip The IP address of the submitter
  * @apiSuccess {String} language The language the ticket was submitted in
@@ -41,7 +41,6 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiSuccess {String} timeWorked The total time worked on the ticket, in `hh:mm:ss`
  * @apiSuccess {Boolean} archive `true` if the ticket is tagged<br>`false` otherwise
  * @apiSuccess {Boolean} locked `true` if the ticket is locked<br>`false` otherwise
- * @apiSuccess {Binary[]} attachments Array of attachments, in base-64 encoded binary
  * @apiSuccess {Integer[]} merged Array of merged ticket IDs
  * @apiSuccess {String} legacyAuditTrail HTML markup of the entire "Audit Trail" section
  * @apiSuccess {String} custom1-20 Custom fields 1-20's values.
@@ -52,6 +51,8 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiSuccess {String} userAgent The user agent of the user who submitted the ticket
  * @apiSuccess {Integer} screenResolutionWidth The width of the screen resolution of the user who submitted the ticket
  * @apiSuccess {Integer} screenResolutionHeight The height of the screen resolution of the user who submitted the ticket
+ * @apiSuccess {Date} dueDate The ticket's due date, if there is one
+ * @apiSuccess {Boolean} overdueEmailSent Set to `true` if an overdue email has been sent.<br>`false` otherwise
  *
  * @apiSuccessExample {json} Success-Response:
  *     HTTP/1.1 200 OK
@@ -102,7 +103,9 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  *           "html": false,
  *           "userAgent": null,
  *           "screenResolutionWidth": null,
- *           "screenResolutionHeight": null
+ *           "screenResolutionHeight": null,
+ *           "dueDate": "2016-01-01 00:00:00",
+ *           "overdueEmailSent": "true"
  *      }
  *
  * @apiError (noTokenProvided) 400 No `X-Auth-Token` was provided where it is required
@@ -110,17 +113,18 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  */
 if ($request_method == 'GET') {
     $token = get_header('X-Auth-Token');
+    $user = NULL;
 
     try {
-        get_user_for_token($token, $hesk_settings);
+        $user = get_user_for_token($token, $hesk_settings);
     } catch (AccessException $e) {
         return http_response_code($e->getCode());
     }
 
     if (isset($_GET['id'])) {
-        $results = get_ticket_for_staff($hesk_settings, $_GET['id']);
+        $results = get_ticket_for_staff($hesk_settings, $user, $_GET['id']);
     } else {
-        $results = get_ticket_for_staff($hesk_settings);
+        $results = get_ticket_for_staff($hesk_settings, $user);
     }
 
     if ($results == NULL) {
diff --git a/api/admin/user/index.php b/api/admin/user/index.php
index 4b980a21..5f62266c 100644
--- a/api/admin/user/index.php
+++ b/api/admin/user/index.php
@@ -20,7 +20,7 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiVersion 0.0.0
  * @apiName GetUser
  * @apiGroup User
- * @apiPermission protected
+ * @apiPermission canManUsers
  *
  * @apiParam {Number} [id] The ID of the user. Omit for all users.
  *
@@ -30,7 +30,6 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiSuccess {String} name The user's name
  * @apiSuccess {String} email The user's email address
  * @apiSuccess {String} signature The user's signature, in plaintext
- * @apiSuccess {Unknown} language ??? (Unknown)
  * @apiSuccess {String[]} categories Ticket categories the user has access to. If the user is an admin, this list has one element: ""
  * @apiSuccess {Integer} afterReply Action to perform after replying to a ticket:<br>
  *     `0` - Show the ticket I just replied to<br>
@@ -55,6 +54,11 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  * @apiSuccess {String} rating The overall rating of the user, as a floating point decimal
  * @apiSuccess {Integer} autorefresh The ticket table autorefresh time for the user, in milliseconds
  * @apiSuccess {Boolean} active `true` if the user is active<br>`false` otherwise
+ * @apiSuccess {Integer} defaultCalendarView The default view displayed on the calendar screen:<br>
+ *     `0` - Month<br>
+ *     `1` - Week<br>
+ *     `2` - Day<br>
+ * @apiSuccess {Boolean} notifyOverdueUnassigned Notify user of overdue tickets assigned to others / not assigned
  *
  * @apiSuccessExample {json} Success-Response:
  *      HTTP/1.1 200 OK
@@ -65,7 +69,6 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  *          "name": "Your name",
  *          "email": "mkoch227@gmail.com",
  *          "signature": "Sincerely,\r\n\r\nYour name\r\nYour website\r\nhttp://www.yourwebsite.com\r\n& < > ^ &",
- *          "language": null,
  *          "categories": [
  *              ""
  *          ],
@@ -91,21 +94,28 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  *          "ratingPos": 0,
  *          "rating": "0",
  *          "autorefresh": 0,
- *          "active": true
+ *          "active": true,
+ *          "defaultCalendarView": 0,
+ *          "notifyOverdueUnassigned": true
  *      }
  *
  * @apiError (noTokenProvided) 400 No `X-Auth-Token` was provided where it is required
- * @apiError (invalidXAuthToken) 401 The `X-Auth-Token` provided was invalid
+ * @apiError (invalidXAuthToken) 401 The `X-Auth-Token` provided was invalid, or the user does not have the 'can_man_users' permission
  */
 if ($request_method == 'GET') {
     $token = get_header('X-Auth-Token');
+    $user = NULL;
 
     try {
-        get_user_for_token($token, $hesk_settings);
+        $user = get_user_for_token($token, $hesk_settings);
     } catch (AccessException $e) {
         return http_response_code($e->getCode());
     }
 
+    if (!$user['isadmin'] && strpos($user['heskprivileges'], 'can_man_users') === false) {
+        return http_response_code(401);
+    }
+
     if (isset($_GET['id'])) {
         $results = retrieve_user($hesk_settings, $_GET['id']);
     } else {
diff --git a/api/businesslogic/ticket_retriever.php b/api/businesslogic/ticket_retriever.php
index b5165292..1f91da1e 100644
--- a/api/businesslogic/ticket_retriever.php
+++ b/api/businesslogic/ticket_retriever.php
@@ -1,8 +1,12 @@
 <?php
 require_once(API_PATH . 'dao/ticket_dao.php');
 
-function get_ticket_for_staff($hesk_settings, $id = NULL) {
-    $tickets = get_ticket_for_id($hesk_settings, $id);
+function get_ticket_for_staff($hesk_settings, $user, $id = NULL) {
+    $tickets = get_ticket_for_id($hesk_settings, $user, $id);
+
+    if ($tickets == NULL) {
+        return NULL;
+    }
 
     if ($id === NULL) {
         $original_tickets = $tickets;
@@ -10,10 +14,12 @@ function get_ticket_for_staff($hesk_settings, $id = NULL) {
         foreach ($original_tickets as $ticket) {
             $ticket = remove_common_properties($ticket);
             $ticket = convert_to_camel_case($ticket);
+            $ticket = handle_dates($ticket);
             $tickets[] = $ticket;
         }
     } else {
         $tickets = remove_common_properties($tickets);
+        $tickets = handle_dates($tickets);
         $tickets = convert_to_camel_case($tickets);
     }
 
@@ -36,27 +42,37 @@ function remove_common_properties($ticket) {
     return $ticket;
 }
 
+function handle_dates($ticket) {
+    $ticket['dt'] = hesk_date($ticket['dt'], true);
+
+    return $ticket;
+}
+
 function convert_to_camel_case($ticket) {
     if (isset($ticket['articles'])) {
         $ticket['suggestedArticles'] = $ticket['articles'];
         unset($ticket['articles']);
-        $ticket['legacyAuditTrail'] = $ticket['history'];
-        unset($ticket['history']);
-        $ticket['linkedTo'] = $ticket['parent'];
-        unset($ticket['parent']);
-        $ticket['timeWorked'] = $ticket['time_worked'];
-        unset($ticket['time_worked']);
-        $ticket['userAgent'] = $ticket['user_agent'];
-        unset($ticket['user_agent']);
-        $ticket['screenResolutionWidth'] = $ticket['screen_resolution_width'];
-        unset($ticket['screen_resolution_width']);
-        $ticket['screenResolutionHeight'] = $ticket['screen_resolution_height'];
-        unset($ticket['screen_resolution_height']);
     }
+    $ticket['legacyAuditTrail'] = $ticket['history'];
+    unset($ticket['history']);
+    $ticket['linkedTo'] = $ticket['parent'];
+    unset($ticket['parent']);
+    $ticket['timeWorked'] = $ticket['time_worked'];
+    unset($ticket['time_worked']);
+    $ticket['userAgent'] = $ticket['user_agent'];
+    unset($ticket['user_agent']);
+    $ticket['screenResolutionWidth'] = $ticket['screen_resolution_width'];
+    unset($ticket['screen_resolution_width']);
+    $ticket['screenResolutionHeight'] = $ticket['screen_resolution_height'];
+    unset($ticket['screen_resolution_height']);
     $ticket['trackingId'] = $ticket['trackid'];
     unset($ticket['trackid']);
     $ticket['dateCreated'] = $ticket['dt'];
     unset($ticket['dt']);
+    $ticket['dueDate'] = $ticket['due_date'];
+    unset($ticket['due_date']);
+    $ticket['overdueEmailSent'] = $ticket['overdue_email_sent'];
+
 
     return $ticket;
 }
@@ -83,6 +99,8 @@ function remove_staff_specific_properties($ticket) {
     unset($ticket['screen_resolution_width']);
     unset($ticket['screen_resolution_height']);
     unset($ticket['parent']);
+    unset($ticket['due_date']);
+    unset($ticket['overdue_email_sent']);
 
     return $ticket;
 }
\ No newline at end of file
diff --git a/api/businesslogic/user_retriever.php b/api/businesslogic/user_retriever.php
index ddfa06ed..c184f5be 100644
--- a/api/businesslogic/user_retriever.php
+++ b/api/businesslogic/user_retriever.php
@@ -68,6 +68,10 @@ function convert_to_camel_case($user) {
     unset($user['ratingpos']);
     $user['heskPrivileges'] = $user['heskprivileges'];
     unset($user['heskprivileges']);
+    $user['defaultCalendarView'] = $user['default_calendar_view'];
+    unset($user['default_calendar_view']);
+    $user['notifyOverdueUnassigned'] = $user['notify_overdue_unassigned'];
+    unset($user['notify_overdue_unassigned']);
 
     return $user;
 }
\ No newline at end of file
diff --git a/api/common_api_doc.php b/api/common_api_doc.php
index 6212e53a..c829a7a6 100644
--- a/api/common_api_doc.php
+++ b/api/common_api_doc.php
@@ -5,8 +5,8 @@
  *
  */
 /**
- * @apiDefine protected Protected
- *      A protected API can only be utilized by those with a valid `X-Auth-Token`.
+ * @apiDefine protected Protected (Any)
+ *      A protected API can only be utilized by any user with a valid `X-Auth-Token`.
  */
 /**
  * @apiDefine invalidXAuthToken 401 Unauthorized
@@ -15,4 +15,7 @@
 /**
  * @apiDefine noTokenProvided 400 Bad Request
  *      No `X-Auth-Token` was provided.
+ *
+ * @apiDefine canManUsers Protected (Can Manage Users)
+ *      A protected API can only be utilized by users with a valid `X-Auth-Token` and have the 'can_man_users' permission (or is an admin)
  */
\ No newline at end of file
diff --git a/api/dao/ticket_dao.php b/api/dao/ticket_dao.php
index 4047d2bf..fbf10fc3 100644
--- a/api/dao/ticket_dao.php
+++ b/api/dao/ticket_dao.php
@@ -1,9 +1,22 @@
 <?php
 
-function get_ticket_for_id($hesk_settings, $id = NULL) {
-    $sql = "SELECT * FROM `" . hesk_dbEscape($hesk_settings['db_pfix']) . "tickets` ";
+function get_ticket_for_id($hesk_settings, $user, $id = NULL) {
+    $sql = "SELECT `tickets`.* FROM `" . hesk_dbEscape($hesk_settings['db_pfix']) . "tickets` AS `tickets` ";
+    $sql .= "INNER JOIN `" . hesk_dbEscape($hesk_settings['db_pfix']) . "users` AS `users` ON `users`.`id` = " . intval($user['id']) . " ";
+    $used_where_clause = false;
     if ($id != NULL) {
-        $sql .= "WHERE `id` = ".intval($id);
+        $used_where_clause = true;
+        $sql .= "WHERE `tickets`.`id` = " . intval($id);
+    }
+
+    if (!$user['isadmin']) {
+        $clause = $used_where_clause ? ' AND ' : ' WHERE ';
+        $used_where_clause = true;
+
+        $sql .= $clause . ' `category` IN (' . $user['categories'] . ')';
+        $sql .= " AND ((`heskprivileges` LIKE '%can_view_tickets%' AND `owner` = " . intval($user['id']) . ")";
+        $sql .= " OR (`heskprivileges` LIKE '%can_view_unassigned%' AND `owner` = 0)";
+        $sql .= " OR (`heskprivileges` LIKE '%can_view_ass_others%' AND `owner` <> " . intval($user['id']) . "))";
     }
 
     $response = hesk_dbQuery($sql);
@@ -32,6 +45,7 @@ function build_results($response) {
         $row['screen_resolution_width'] = convert_to_int($row['screen_resolution_width']);
         $row['owner'] = convert_to_int($row['owner']);
         $row['parent'] = convert_to_int($row['parent']);
+        $row['overdue_email_sent'] = $row['overdue_email_sent'] == true;
 
 
         $results[] = $row;
diff --git a/api/dao/user_dao.php b/api/dao/user_dao.php
index b7bdde12..e7b343c8 100644
--- a/api/dao/user_dao.php
+++ b/api/dao/user_dao.php
@@ -36,6 +36,8 @@ function get_user($hesk_settings, $id = NULL) {
         $row['ratingpos'] = intval($row['ratingpos']);
         $row['autorefresh'] = intval($row['autorefresh']);
         $row['active'] = get_boolean($row['active']);
+        $row['default_calendar_view'] = intval($row['default_calendar_view']);
+        $row['notify_overdue_unassigned'] = get_boolean($row['notify_overdue_unassigned']);
 
 
         // TODO: Remove this once GitHub #346 is complete
diff --git a/api/ticket/index.php b/api/ticket/index.php
index 4f48fe32..f4f7c9c8 100644
--- a/api/ticket/index.php
+++ b/api/ticket/index.php
@@ -78,7 +78,7 @@ $request_method = $_SERVER['REQUEST_METHOD'];
  *           "custom18": "",
  *           "custom19": "",
  *           "custom20": "",
- *           "html": false,
+ *           "html": false
  *      }
  *
  * @apiError (noTokenProvided) 400 No `X-Auth-Token` was provided where it is required
diff --git a/internal-api/admin/api-authentication/index.php b/internal-api/admin/api-authentication/index.php
index eb922362..8692b19b 100644
--- a/internal-api/admin/api-authentication/index.php
+++ b/internal-api/admin/api-authentication/index.php
@@ -4,15 +4,23 @@ define('HESK_PATH', '../../../');
 define('INTERNAL_API_PATH', '../../');
 require_once(HESK_PATH . 'hesk_settings.inc.php');
 require_once(HESK_PATH . 'inc/common.inc.php');
+require_once(HESK_PATH . 'inc/admin_functions.inc.php');
 require_once(INTERNAL_API_PATH . 'core/output.php');
 require_once(INTERNAL_API_PATH . 'dao/api_authentication_dao.php');
 
+hesk_session_start();
 hesk_load_internal_api_database_functions();
 hesk_dbConnect();
 
 // Routing
 $request_method = $_SERVER['REQUEST_METHOD'];
 if ($request_method == 'POST') {
+
+    if (!isset($_SESSION['heskprivileges']) || !hesk_checkPermission('can_man_settings', 0)) {
+        print_error('Access Denied', 'Access Denied!');
+        return http_response_code(401);
+    }
+
     $user_id = $_POST['userId'];
     $action = $_POST['action'];
 
diff --git a/internal-api/admin/api-settings/index.php b/internal-api/admin/api-settings/index.php
index beb5cffe..d2d241bc 100644
--- a/internal-api/admin/api-settings/index.php
+++ b/internal-api/admin/api-settings/index.php
@@ -4,12 +4,19 @@ define('HESK_PATH', '../../../');
 define('INTERNAL_API_PATH', '../../');
 require_once(HESK_PATH . 'hesk_settings.inc.php');
 require_once(HESK_PATH . 'inc/common.inc.php');
+require_once(HESK_PATH . 'inc/admin_functions.inc.php');
 require_once(INTERNAL_API_PATH . 'core/output.php');
 require_once(INTERNAL_API_PATH . 'dao/settings_dao.php');
 
+hesk_session_start();
 hesk_load_internal_api_database_functions();
 hesk_dbConnect();
 
+if (!isset($_SESSION['heskprivileges']) || !hesk_checkPermission('can_man_settings', 0)) {
+    print_error('Access Denied', 'Access Denied!');
+    return http_response_code(401);
+}
+
 // Routing
 $request_method = $_SERVER['REQUEST_METHOD'];
 if ($request_method == 'POST') {
diff --git a/internal-api/admin/calendar/index.php b/internal-api/admin/calendar/index.php
index 623b1ff6..512d6ac3 100644
--- a/internal-api/admin/calendar/index.php
+++ b/internal-api/admin/calendar/index.php
@@ -24,6 +24,11 @@ if ($request_method === 'GET') {
 
     return output($events);
 } elseif ($request_method === 'POST') {
+    if ($request_method !== 'update-ticket' && !hesk_checkPermission('can_man_calendar', 0)) {
+        print_error('Access Denied', 'Access Denied!');
+        return http_response_code(401);
+    }
+
     $action = hesk_POST('action');
 
     if ($action === 'create') {