[3.x] send emails to dotless domains

Now that we are using phpmailer 6'+ this code block is not needed as it is now the default. However it does not support dotless domains which joomla supports so we still need to set a validator.

this is a backport of #28574

technically this pr is a b/c break as it allows dotless domains and it has not allowed allowed dotless domains since #24726 was merged but its much more of a bug fix as we should have allowed dotless domains and that pr broke it

libraries/src/Mail/Mail.php

@@ -65,16 +65,23 @@ public function __construct($exceptions = true)
 		// Don't disclose the PHPMailer version
 		$this->XMailer = ' ';
 
-		/*
-		 * PHPMailer 5.2 can't validate e-mail addresses with the new regex library used in PHP 7.3+
-		 * Setting $validator to "php" uses the native php function filter_var
-		 *
-		 * @see https://github.com/joomla/joomla-cms/issues/24707
-		 */
-		if (version_compare(PHP_VERSION, '7.3.0', '>='))
-		{
-			\PHPMailer::$validator = 'php';
-		}
+		/**
+		* Which validator to use by default when validating email addresses.
+		* Validation patterns supported:
+		* `auto` Pick best pattern automatically;
+		* `pcre8` Use the squiloople.com pattern, requires PCRE > 8.0;
+		* `pcre` Use old PCRE implementation;
+		* `php` Use PHP built-in FILTER_VALIDATE_EMAIL;
+		* `html5` Use the pattern given by the HTML5 spec for 'email' type form input elements.
+		* `noregex` Don't use a regex: super fast, really dumb.
+		*
+		* The default used by phpmailer is `php` but this does not support dotless domains so instead we use `html5`
+		*
+		* @see PHPMailer::validateAddress()
+		*
+		* @var string|callable
+		*/
+		PHPMailer::$validator = 'html5';
 	}
 
 	/**