diff --git a/phpBB/includes/acp/acp_email.php b/phpBB/includes/acp/acp_email.php
index 677cea26b5..9d8657a294 100644
--- a/phpBB/includes/acp/acp_email.php
+++ b/phpBB/includes/acp/acp_email.php
@@ -227,25 +227,34 @@ class acp_email
 
 					foreach ($messenger_collection_iterator as $messenger_method)
 					{
-						if ($messenger_method->get_id() == $used_method || $used_method == NOTIFY_BOTH)
+						$notify_method = $messenger_method->get_id();
+						if ($notify_method == $used_method || $used_method == NOTIFY_BOTH)
 						{
 							$messenger_method->set_use_queue($use_queue);
 							$messenger_method->template($email_template, $used_lang);
 							$messenger_method->subject(html_entity_decode($subject, ENT_COMPAT));
 							$messenger_method->assign_vars($template_data);
 
-							if ($messenger_method->get_id() == NOTIFY_EMAIL)
+							if ($notify_method == NOTIFY_EMAIL)
 							{
 								for ($j = 0, $list_size = count($email_list[$i]); $j < $list_size; $j++)
 								{
 									$email_row = $email_list[$i][$j];
-									$messenger_method->{((count($email_list[$i]) == 1) ? 'to' : 'bcc')}($email_row['email'], $email_row['name']);
+									if (count($email_list[$i]) == 1)
+									{
+										$messenger_method->to($email_row['email'], $email_row['name']);
+									
+									}
+									else
+									{
+										$messenger_method->bcc($email_row['email'], $email_row['name']);
+									}
 								}
 
 								$messenger_method->anti_abuse_headers($config, $user);
 								$messenger_method->set_mail_priority($priority);
 							}
-							else if ($messenger_method->get_id() == NOTIFY_JABBER)
+							else if ($notify_method == NOTIFY_IM)
 							{
 								for ($j = 0, $list_size = count($email_list[$i]); $j < $list_size; $j++)
 								{
@@ -254,7 +263,7 @@ class acp_email
 								}
 							}
 
-							$errored = !$messenger_method->send();
+							$errored = !$messenger_method->send() || $errored;
 							if ($use_queue)
 							{
 								$messenger_method->save_queue();
diff --git a/phpBB/includes/ucp/ucp_resend.php b/phpBB/includes/ucp/ucp_resend.php
index ab108bc15d..278c086a8b 100644
--- a/phpBB/includes/ucp/ucp_resend.php
+++ b/phpBB/includes/ucp/ucp_resend.php
@@ -92,6 +92,7 @@ class ucp_resend
 				trigger_error('NO_GROUP');
 			}
 
+			$board_url = generate_board_url();
 			$coppa = ($row['group_name'] == 'REGISTERED_COPPA' && $row['group_type'] == GROUP_SPECIAL) ? true : false;
 
 			$email_method = $phpbb_container->get('messenger.method.email');
@@ -107,7 +108,7 @@ class ucp_resend
 				$email_method->assign_vars([
 					'WELCOME_MSG'	=> html_entity_decode(sprintf($user->lang['WELCOME_SUBJECT'], $config['sitename']), ENT_COMPAT),
 					'USERNAME'		=> html_entity_decode($user_row['username'], ENT_COMPAT),
-					'U_ACTIVATE'	=> generate_board_url() . "/ucp.$phpEx?mode=activate&u={$user_row['user_id']}&k={$user_row['user_actkey']}",
+					'U_ACTIVATE'	=> $board_url . "/ucp.$phpEx?mode=activate&u={$user_row['user_id']}&k={$user_row['user_actkey']}",
 				]);
 
 				if ($coppa)
@@ -145,8 +146,8 @@ class ucp_resend
 							$messenger_method->anti_abuse_headers($config, $user);
 							$messenger_method->assign_vars([
 								'USERNAME'			=> html_entity_decode($user_row['username'], ENT_COMPAT),
-								'U_USER_DETAILS'	=> generate_board_url() . "/memberlist.$phpEx?mode=viewprofile&u={$user_row['user_id']}",
-								'U_ACTIVATE'		=> generate_board_url() . "/ucp.$phpEx?mode=activate&u={$user_row['user_id']}&k={$user_row['user_actkey']}",
+								'U_USER_DETAILS'	=> $board_url . "/memberlist.$phpEx?mode=viewprofile&u={$user_row['user_id']}",
+								'U_ACTIVATE'		=> $board_url . "/ucp.$phpEx?mode=activate&u={$user_row['user_id']}&k={$user_row['user_actkey']}",
 							]);
 
 							$messenger_method->send();
diff --git a/phpBB/phpbb/messenger/method/base.php b/phpBB/phpbb/messenger/method/base.php
index 15fa782d18..46d676013c 100644
--- a/phpBB/phpbb/messenger/method/base.php
+++ b/phpBB/phpbb/messenger/method/base.php
@@ -117,8 +117,8 @@ abstract class base implements messenger_interface
 		service_collection $twig_extensions_collection,
 		lexer $twig_lexer,
 		user $user,
-		$phpbb_root_path,
-		$template_cache_path,
+		string $phpbb_root_path,
+		string $template_cache_path,
 		?manager $ext_manager = null,
 		?log_interface $log = null
 	)
@@ -154,6 +154,8 @@ abstract class base implements messenger_interface
 	/**
 	 * Sets the use of messenger queue flag
 	 *
+	 * @param bool $use_queue Flag indicating if cached queue to be used
+	 *
 	 * @return void
 	 */
 	public function set_use_queue(bool $use_queue = true): void
@@ -426,7 +428,6 @@ abstract class base implements messenger_interface
 		if ($this->use_queue && !empty($this->queue))
 		{
 			$this->queue->save();
-			return;
 		}
 	}
 
diff --git a/phpBB/phpbb/messenger/method/email.php b/phpBB/phpbb/messenger/method/email.php
index c33f048fcc..a8927c23e3 100644
--- a/phpBB/phpbb/messenger/method/email.php
+++ b/phpBB/phpbb/messenger/method/email.php
@@ -110,9 +110,7 @@ class email extends base
 	}
 
 	/**
-	 * Sets the use of messenger queue flag
-	 *
-	 * @return void
+	 * {@inheritdoc}
 	 */
 	public function set_use_queue(bool $use_queue = true): void
 	{
@@ -124,7 +122,7 @@ class email extends base
 	 */
 	public function set_addresses(array $user_row): void
 	{
-		if (isset($user_row['user_email']) && $user_row['user_email'])
+		if (!empty($user_row['user_email']))
 		{
 			$this->to($user_row['user_email'], $user_row['username'] ?: '');
 		}
@@ -295,8 +293,8 @@ class email extends base
 			'Return-Path'		=> new Address($this->config['board_email']),
 			'Sender'			=> new Address($this->config['board_email']),
 			'X-MSMail-Priority'	=> self::PRIORITY_MAP[$this->mail_priority],
-			'X-Mailer'			=> 'phpBB3',
-			'X-MimeOLE'			=> 'phpBB3',
+			'X-Mailer'			=> 'phpBB',
+			'X-MimeOLE'			=> 'phpBB',
 			'X-phpBB-Origin'	=> 'phpbb://' . str_replace(['http://', 'https://'], ['', ''], generate_board_url()),
 		];
 
@@ -472,6 +470,7 @@ class email extends base
 		$this->email->subject($this->subject);
 		$this->email->text($this->msg);
 
+		$break = false;
 		$subject = $this->subject;
 		$msg = $this->msg;
 		$email = $this->email;
@@ -479,13 +478,15 @@ class email extends base
 		 * Event to send message via external transport
 		 *
 		 * @event core.notification_message_email
+		 * @var	bool	break	Flag indicating if the function return after hook
 		 * @var	string	subject	The message subject
 		 * @var	string	msg		The message text
 		 * @var	string	email	The Symfony Email object
 		 * @since 3.2.4-RC1
-		 * @changed 4.0.0-a1 Added vars: email. Removed vars: addresses, break
+		 * @changed 4.0.0-a1 Added vars: email. Removed vars: addresses
 		 */
 		$vars = [
+			'break',
 			'subject',
 			'msg',
 			'email',
@@ -495,6 +496,11 @@ class email extends base
 
 		$this->build_headers();
 
+		if ($break)
+		{
+			return true;
+		}
+
 		// Send message ...
 		if (!$this->use_queue)
 		{
diff --git a/phpBB/phpbb/messenger/method/jabber.php b/phpBB/phpbb/messenger/method/jabber.php
index 199adcd65a..b4fab79574 100644
--- a/phpBB/phpbb/messenger/method/jabber.php
+++ b/phpBB/phpbb/messenger/method/jabber.php
@@ -191,7 +191,7 @@ class jabber extends base
 	 */
 	public function port(int $port = 5222): self
 	{
-		$this->port	= ($port) ? $port : 5222;
+		$this->port	= ($port > 0) ? $port : 5222;
 
 		// Change port if we use SSL
 		if ($this->port == 5222 && $this->use_ssl)
@@ -210,15 +210,15 @@ class jabber extends base
 	 */
 	public function username(string $username = ''): self
 	{
-		if (strpos($username, '@') === false)
-		{
-			$this->username = $username;
-		}
-		else
+		if (str_contains($username, '@'))
 		{
 			$this->jid = explode('@', $username, 2);
 			$this->username = $this->jid[0];
 		}
+		else
+		{
+			$this->username = $username;
+		}
 
 		return $this;
 	}
@@ -232,7 +232,7 @@ class jabber extends base
 	 */
 	public function server(string $server = ''): self
 	{
-		$this->connect_server = ($server) ? $server : 'localhost';
+		$this->connect_server = $server ?: 'localhost';
 		$this->server = $this->jid[1] ?? $this->connect_server;
 
 		return $this;
@@ -407,7 +407,7 @@ class jabber extends base
 	}
 
 	/**
-	 * {@inheritDoc}
+	 * Resets all the data (address, template file, etc) to default
 	 */
 	public function reset(): void
 	{
@@ -663,7 +663,7 @@ class jabber extends base
 	}
 
 	/**
-	 * Initiates account registration (based on data used for contructor)
+	 * Initiates account registration (based on data used for constructor)
 	 *
 	 * @return bool|null
 	 */
@@ -714,7 +714,7 @@ class jabber extends base
 	 */
 	function response(array $xml): bool
 	{
-		if (!is_array($xml) || !count($xml))
+		if (!count($xml))
 		{
 			return false;
 		}
diff --git a/phpBB/phpbb/notification/method/messenger_base.php b/phpBB/phpbb/notification/method/messenger_base.php
index 97994f84af..4aaf01c133 100644
--- a/phpBB/phpbb/notification/method/messenger_base.php
+++ b/phpBB/phpbb/notification/method/messenger_base.php
@@ -112,7 +112,6 @@ abstract class messenger_base extends \phpbb\notification\method\base
 				continue;
 			}
 
-			/** @psalm-suppress InvalidTemplateParam */
 			$messenger_collection_iterator = $this->messenger->getIterator();
 			foreach ($messenger_collection_iterator as $messenger_method)
 			{
diff --git a/phpBB/phpbb/template/twig/extension.php b/phpBB/phpbb/template/twig/extension.php
index fa9fca0705..96a1aa91f1 100644
--- a/phpBB/phpbb/template/twig/extension.php
+++ b/phpBB/phpbb/template/twig/extension.php
@@ -14,6 +14,9 @@
 namespace phpbb\template\twig;
 
 use Twig\Error\RuntimeError;
+use Twig\Extension\CoreExtension;
+use Twig\Extension\EscaperExtension;
+use Twig\Runtime\EscaperRuntime;
 
 class extension extends \Twig\Extension\AbstractExtension
 {
@@ -164,8 +167,7 @@ class extension extends \Twig\Extension\AbstractExtension
 		// We always include the last element (this was the past design)
 		$end = ($end == -1 || $end === null) ? null : $end + 1;
 
-		/** @psalm-suppress UndefinedFunction */
-		return twig_slice($env, $item, $start, $end, $preserveKeys);
+		return CoreExtension::slice($env->getCharset(), $item, $start, $end, $preserveKeys);
 	}
 
 	/**
@@ -214,8 +216,7 @@ class extension extends \Twig\Extension\AbstractExtension
 	{
 		$args = func_get_args();
 
-		/** @psalm-suppress UndefinedFunction */
-		return twig_escape_filter($this->environment, call_user_func_array([$this, 'lang'], $args), 'js');
+		return $this->environment->getRuntime(EscaperRuntime::class)->escape(call_user_func_array([$this, 'lang'], $args), 'js');
 	}
 
 	/**