old code added back

--- lib/private/User/Manager.php	2023-02-03 17:18:44.729561986 +0530

--- lib/private/User/Manager.php	2023-02-03 17:18:44.729561986 +0530

+++ lib/private/User/Manager-new.php	2023-02-03 17:20:18.929562546 +0530

+++ lib/private/User/Manager-new.php	2023-02-03 18:00:50.509563655 +0530

@@ -705,16 +705,18 @@

@@ -705,6 +705,18 @@

 	 * @since 9.1.0

 	 * @since 9.1.0

 	 */

 	 */

 	public function getByEmail($email) {

 	public function getByEmail($email) {

-		// looking for 'email' only (and not primary_mail) is intentional

-		$userIds = $this->config->getUsersForUserValueCaseInsensitive('settings', 'email', $email);

+		$uid=$email; // get first part of email if it contains alt domain, otherwise it is just $email

+		$uid=$email; // get first part of email if it contains alt domain, otherwise it is just $email

+		$alt_domain = $this->config->getSystemValue('alt_mail_domain', '');

+		$alt_domain = $this->config->getSystemValue('alt_mail_domain', '');

+		$alt_domain_suffix = !empty($alt_domain) ? '@'  . $alt_domain : '';

+		$alt_domain_suffix = !empty($alt_domain) ? '@'  . $alt_domain : '';

+

-		$users = array_map(function ($uid) {

-			return $this->get($uid);

-		}, $userIds);

+		if (stristr($email, $alt_domain_suffix) !== FALSE) {

+		if (stristr($email, $alt_domain_suffix) !== FALSE) {

+				$uid = str_replace($alt_domain_suffix, '', $email);

+				$uid = str_replace($alt_domain_suffix, '', $email);

+		}

+		}

+

-		return array_values(array_filter($users, function ($u) {

-			return ($u instanceof IUser);

-		}));

+		if ($this->get($uid)) {

+		if ($this->get($uid)) {

+			return([$this->get($uid)]);

+			return([$this->get($uid)]);

+		}

+		}

+		  return [];

+

 	}

 		// looking for 'email' only (and not primary_mail) is intentional

 		$userIds = $this->config->getUsersForUserValueCaseInsensitive('settings', 'email', $email);

 	private function verifyUid(string $uid): bool {