Update and Remove isValidEmail

change function calls, and remove unneeded function.

mod/dirfind.php

@@ -53,7 +53,7 @@ function dirfind_content(App $a, $prefix = "") {
 	if (strpos($search,'@') === 0) {
 		$search = substr($search,1);
 		$header = L10n::t('People Search - %s', $search);
-		if ((Strings::isValidEmail($search) && Network::isEmailDomainValid($search)) ||
+		if ((filter_var($search, FILTER_VALIDATE_EMAIL) && Network::isEmailDomainValid($search)) ||
 			(substr(Strings::normaliseLink($search), 0, 7) == "http://")) {
 			$user_data = Probe::uri($search);
 			$discover_user = (in_array($user_data["network"], [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::OSTATUS, Protocol::DIASPORA]));

mod/invite.php

@@ -56,7 +56,7 @@ function invite_post(App $a)
 	foreach ($recipients as $recipient) {
 		$recipient = trim($recipient);
 
-		if (! Strings::isValidEmail($recipient)) {
+		if (!filter_var($recipient, FILTER_VALIDATE_EMAIL)) {
 			notice(L10n::t('%s : Not a valid email address.', $recipient) . EOL);
 			continue;
 		}

mod/settings.php

@@ -517,7 +517,7 @@ function settings_post(App $a)
 			$email = $a->user['email'];
 		}
 		//  check the email is valid
-		if (!Strings::isValidEmail($email)) {
+		if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
 			$err .= L10n::t('Invalid email.');
 		}
 		//  ensure new email is not the admin mail

src/Model/User.php

@@ -499,7 +499,7 @@ class User
 			throw new Exception(L10n::t('Your email domain is not among those allowed on this site.'));
 		}
 
-		if (!Strings::isValidEmail($email) || !Network::isEmailDomainValid($email)) {
+		if (!filter_var($email, FILTER_VALIDATE_EMAIL) || !Network::isEmailDomainValid($email)) {
 			throw new Exception(L10n::t('Not a valid email address.'));
 		}
 		if (self::isNicknameBlocked($nickname)) {

src/Util/Strings.php

@@ -353,18 +353,6 @@ class Strings
         return $ret;
     }
 
-    /**
-     * @brief Check for a valid email string
-     *
-     * @param string $email_address Email address to be evaluated.
-     * 
-     * @return boolean  Value indicating whether or not the string is a valid email address.
-     */
-    public static function isValidEmail($email_address)
-    {
-        return preg_match('/^[_a-zA-Z0-9\-\+]+(\.[_a-zA-Z0-9\-\+]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)+$/', $email_address);
-    }
-
     /**
      * @brief Normalize url
      *