diff --git a/lib/Config/Migrator.php b/lib/Config/Migrator.php
index b8342b4cd3..42bcbc1dc1 100644
--- a/lib/Config/Migrator.php
+++ b/lib/Config/Migrator.php
@@ -172,7 +172,8 @@ class Migrator {
       'deleted_at TIMESTAMP NULL,',
       'unconfirmed_data longtext,',
       'PRIMARY KEY  (id),',
-      'UNIQUE KEY email (email)'
+      'UNIQUE KEY email (email),',
+      'KEY wp_user_id (wp_user_id)',
     );
     return $this->sqlify(__FUNCTION__, $attributes);
   }
diff --git a/lib/Segments/WP.php b/lib/Segments/WP.php
index eceaecccca..44152419ef 100644
--- a/lib/Segments/WP.php
+++ b/lib/Segments/WP.php
@@ -79,28 +79,109 @@ class WP {
   }
 
   static function synchronizeUsers() {
-    // get wordpress users list
+
+    self::updateSubscribersEmails();
+    self::insertSubscribers();
+    self::removeFromTrash();
+    self::updateFirstNames();
+    self::updateLastNames();
+    self::updateFristNameIfMissing();
+    self::insertUsersToSegment();
+    self::removeOrphanedSubscribers();
+
+    return true;
+  }
+
+  private static function updateSubscribersEmails() {
+    global $wpdb;
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      UPDATE IGNORE %s
+        JOIN %susers as wu ON %s.wp_user_id = wu.id
+      SET email = user_email
+        WHERE %s.wp_user_id IS NOT NULL
+    ', $subscribers_table, $wpdb->prefix, $subscribers_table, $subscribers_table));
+  }
+
+  private static function insertSubscribers() {
+    global $wpdb;
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      INSERT IGNORE INTO %s(wp_user_id, email, status, created_at)
+        SELECT wu.id, wu.user_email, "subscribed", CURRENT_TIMESTAMP() FROM %susers wu
+          LEFT JOIN %s mps ON wu.id = mps.wp_user_id
+          WHERE mps.wp_user_id IS NULL
+    ', $subscribers_table, $wpdb->prefix, $subscribers_table));
+  }
+
+  private static function updateFirstNames() {
+    global $wpdb;
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      UPDATE %s
+        JOIN %susermeta as wpum ON %s.wp_user_id = wpum.user_id AND meta_key = "first_name"
+      SET first_name = meta_value
+        WHERE %s.first_name = ""
+        AND %s.wp_user_id IS NOT NULL
+    ', $subscribers_table, $wpdb->prefix, $subscribers_table, $subscribers_table, $subscribers_table));
+  }
+
+  private static function updateLastNames() {
+    global $wpdb;
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      UPDATE %s
+        JOIN %susermeta as wpum ON %s.wp_user_id = wpum.user_id AND meta_key = "last_name"
+      SET last_name = meta_value
+        WHERE %s.last_name = ""
+        AND %s.wp_user_id IS NOT NULL
+    ', $subscribers_table, $wpdb->prefix, $subscribers_table, $subscribers_table, $subscribers_table));
+  }
+
+  private static function updateFristNameIfMissing() {
+    global $wpdb;
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      UPDATE %s
+        JOIN %susers wu ON %s.wp_user_id = wu.id
+      SET first_name = display_name
+        WHERE %s.first_name = ""
+        AND %s.wp_user_id IS NOT NULL
+    ', $subscribers_table, $wpdb->prefix, $subscribers_table, $subscribers_table, $subscribers_table));
+  }
+
+  private static function insertUsersToSegment() {
     $wp_segment = Segment::getWPSegment();
+    $subscribers_table = Subscriber::$_table;
+    $wp_mailpoet_subscriber_segment_table = SubscriberSegment::$_table;
+    Subscriber::raw_execute(sprintf('
+     INSERT IGNORE INTO %s(subscriber_id, segment_id, created_at)
+      SELECT mps.id, "%s", CURRENT_TIMESTAMP() FROM %s mps
+        WHERE mps.wp_user_id IS NOT NULL
+    ', $wp_mailpoet_subscriber_segment_table, $wp_segment->id, $subscribers_table));
+  }
 
-    // fetch all wp users id
-    $wp_users = \get_users(array(
-      'count_total'  => false,
-      'fields' => 'ID'
-    ));
-
-    // update data for each wp user
-    foreach($wp_users as $wp_user_id) {
-      static::synchronizeUser($wp_user_id);
-    }
+  private static function removeFromTrash() {
+    $subscribers_table = Subscriber::$_table;
+    Subscriber::raw_execute(sprintf('
+      UPDATE %s       
+      SET deleted_at = NULL
+        WHERE %s.wp_user_id IS NOT NULL
+    ', $subscribers_table, $subscribers_table));
+  }
 
+  private static function removeOrphanedSubscribers() {
     // remove orphaned wp segment subscribers (not having a matching wp user id),
     // e.g. if wp users were deleted directly from the database
-    $wp_segment->subscribers()
-      ->whereNotIn('wp_user_id', $wp_users)
+    global $wpdb;
+
+    Subscriber::table_alias('wpms')
+      ->leftOuterJoin($wpdb->prefix . 'users', array('wpms.wp_user_id', '=', 'wu.id'), 'wu')
+      ->whereNull('wu.id')
       ->findResultSet()
       ->set('wp_user_id', null)
       ->delete();
 
-    return true;
   }
 }
+
diff --git a/tests/unit/Segments/WPTest.php b/tests/unit/Segments/WPTest.php
index 8a45c6c2f8..da1d2d9b7f 100644
--- a/tests/unit/Segments/WPTest.php
+++ b/tests/unit/Segments/WPTest.php
@@ -1,55 +1,194 @@
 <?php
-namespace MailPoet\Test\Segments;
 
-use MailPoet\Models\Segment;
-use MailPoet\Segments\WP;
+namespace MailPoet\Test\Segments;
 
 require_once(ABSPATH . 'wp-admin/includes/user.php');
 
-class WPTest extends \MailPoetTest {
-  function _before() {
-    $this->wp_user_1 = $this->createWPUser('phoenix_test_user');
-    $this->wp_user_2 = $this->createWPUser('phoenix_test_user2');
-    $this->wp_segment = Segment::getWPSegment();
+use Carbon\Carbon;
+use MailPoet\Models\Segment;
+use MailPoet\Models\Subscriber;
+use MailPoet\Segments\WP;
+
+class WPTest extends \MailPoetTest  {
+
+  private $userIds = array();
+
+  function testItSynchronizeUsers() {
+    $this->insertUser();
+    $this->insertUser();
+    WP::synchronizeUsers();
+    $subscribersCount = $this->getSubscribersCount();
+    expect($subscribersCount)->equals(2);
+  }
+
+  function testItSynchronizeNewUsers() {
+    $this->insertUser();
+    $this->insertUser();
+    WP::synchronizeUsers();
+    $this->insertUser();
+    WP::synchronizeUsers();
+    $subscribersCount = $this->getSubscribersCount();
+    expect($subscribersCount)->equals(3);
+  }
+
+  function testItSynchronizeEmails() {
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    $this->updateWPUserEmail($id, 'user-sync-test-xx@email.com');
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where('wp_user_id', $id)->findOne();
+    expect($subscriber->email)->equals('user-sync-test-xx@email.com');
+  }
+
+  function testItSynchronizeFirstNames() {
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    update_user_meta($id, 'first_name', 'First name');
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where('wp_user_id', $id)->findOne();
+    expect($subscriber->first_name)->equals('First name');
+  }
+
+  function testItSynchronizeLastNames() {
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    update_user_meta($id, 'last_name', 'Last name');
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where('wp_user_id', $id)->findOne();
+    expect($subscriber->last_name)->equals('Last name');
+  }
+
+  function testItSynchronizeFirstNamesUsingDisplayName() {
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    $this->updateWPUserDisplayName($id, 'First name');
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where('wp_user_id', $id)->findOne();
+    expect($subscriber->first_name)->equals('First name');
+  }
+
+  function testItSynchronizeSegment() {
+    $this->insertUser();
+    $this->insertUser();
+    $this->insertUser();
+    WP::synchronizeUsers();
+    $subscribers = Segment::getWPSegment()->subscribers()->whereIn('wp_user_id', $this->userIds);
+    expect($subscribers->count())->equals(3);
+  }
+
+  function testItRemovesUsersFromTrash() {
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where("wp_user_id", $id)->findOne();
+    $subscriber->deleted_at = Carbon::now();
+    $subscriber->save();
+    WP::synchronizeUsers();
+    $subscriber = Subscriber::where("wp_user_id", $id)->findOne();
+    expect($subscriber->deleted_at)->null();
   }
 
   function testItSynchronizesDeletedWPUsersUsingHooks() {
-    expect($this->getWPSegmentSubscribers()->count())->equals(2);
-    wp_delete_user($this->wp_user_1->ID);
-    expect($this->getWPSegmentSubscribers()->count())->equals(1);
-  }
-
-  function testItForciblySynchronizesDeletedWPUsers() {
-    global $wpdb;
-    expect($this->getWPSegmentSubscribers()->count())->equals(2);
-    // Remove a WP user directly from the database
-    \ORM::for_table($wpdb->prefix . 'users')
-      ->where('id', $this->wp_user_2->ID)
-      ->deleteMany();
+    $id = $this->insertUser();
+    $this->insertUser();
     WP::synchronizeUsers();
-    expect($this->getWPSegmentSubscribers()->count())->equals(1);
+    $subscribersCount = $this->getSubscribersCount();
+    expect($subscribersCount)->equals(2);
+    wp_delete_user($id);
+    $subscribersCount = $this->getSubscribersCount();
+    expect($subscribersCount)->equals(1);
   }
 
-  private function getWPSegmentSubscribers() {
-    return $this->wp_segment->subscribers()
-      ->whereIn(
-        'wp_user_id',
-        array(
-          $this->wp_user_1->ID,
-          $this->wp_user_2->ID
-        )
-      );
+  function testItRemovesOrphanedSubscribers() {
+    $this->insertUser();
+    $id = $this->insertUser();
+    WP::synchronizeUsers();
+    $this->deleteWPUser($id);
+    WP::synchronizeUsers();
+    $subscribers = Segment::getWPSegment()->subscribers()->whereIn('wp_user_id', $this->userIds);
+    expect($subscribers->count())->equals(1);
   }
 
-  private function createWPUser($login) {
-    $WP_user = wp_create_user($login, 'pass', $login . '@example.com');
-    $WP_user = get_user_by('login', $login);
-    return $WP_user;
+  function _before() {
+    $this->cleanData();
   }
 
   function _after() {
-    \ORM::raw_execute('TRUNCATE ' . Segment::$_table);
-    wp_delete_user($this->wp_user_1->ID);
-    wp_delete_user($this->wp_user_2->ID);
+    $this->cleanData();
   }
-}
+
+  private function cleanData() {
+    \ORM::raw_execute('TRUNCATE ' . Segment::$_table);
+    global $wpdb;
+    $db = \ORM::getDb();
+    $db->exec(sprintf('
+       DELETE FROM
+         %susers       
+       WHERE
+         user_email LIKE "user-sync-test%%"
+    ', $wpdb->prefix));
+  }
+
+  private function getSubscribersCount() {
+    return Subscriber::whereIn("wp_user_id", $this->userIds)->count();
+  }
+
+  /**
+   * Insert a user without invoking wp hooks.
+   * Those tests are testing user synchronisation, so we need data in wp_users table which has not been synchronised to
+   * mailpoet database yet. We cannot use wp_insert_user functions because they would do the sync on insert.
+   *
+   * @return string
+   */
+  private function insertUser() {
+    global $wpdb;
+    $db = \ORM::getDb();
+    $db->exec(sprintf('
+         INSERT INTO 
+           %susers(user_login, user_email, user_registered) 
+           VALUES 
+           (
+             CONCAT("user-sync-test", rand()), 
+             CONCAT("user", rand(), "@example.com"),
+             "2017-01-02 12:31:12"
+           )', $wpdb->prefix));
+    $id = $db->lastInsertId();
+    $this->userIds[] = $id;
+    return $id;
+  }
+
+  private function updateWPUserEmail($id, $email) {
+    global $wpdb;
+    $db = \ORM::getDb();
+    $db->exec(sprintf('
+       UPDATE
+         %susers
+       SET user_email = "%s"
+       WHERE
+         id = %s
+    ', $wpdb->prefix, $email, $id));
+  }
+
+  private function updateWPUserDisplayName($id, $name) {
+    global $wpdb;
+    $db = \ORM::getDb();
+    $db->exec(sprintf('
+       UPDATE
+         %susers
+       SET display_name = "%s"
+       WHERE
+         id = %s
+    ', $wpdb->prefix, $name, $id));
+  }
+
+  private function deleteWPUser($id) {
+    global $wpdb;
+    $db = \ORM::getDb();
+    $db->exec(sprintf('
+       DELETE FROM
+         %susers       
+       WHERE
+         id = %s
+    ', $wpdb->prefix, $id));
+  }
+
+}
\ No newline at end of file