Cakephp import users failed due to unique rule for email addresses

I am trying to import users into the db using cakephp 3. It is working, but due to a rule I added, when an email address is being imported that already exists, it fails (rollback kicks in). This is the code for the rule:

public function buildRules(RulesChecker $rules)
    $rules->add($rules->isUnique(['email'], 'Email ID Already Exists'));
    return $rules;

Now what I want to know is, how can I skip a record that does already exists and continue to the next one.

Here is part of the code I use to save the array of users:

$usersTable = TableRegistry::getTableLocator()->get('users');

$useritems = $usersTable->newEntities($new_array, [
    'validate' => 'get_users_from_google'

if ($usersTable->saveMany($useritems)) {
    echo json_encode('success', 1);
    echo json_encode('failed', 1);

This code is part of a function which is called via ajax.

Instead of trying to save everything using saveMany, loop through each User you want to save:

// keep track of whether there were any errors
$complete_success = true;

foreach ( $new_array as $user_data ) {
	$user = $usersTable->newEntity( $user_data, [ 'validate' => 'get_users_from_google' ] );

	// check to see if the User was saved successfully; in this case NOT saved successfully
    if ( !$usersTable->save( $user ) ) {
		$complete_success = false;

if ( $complete_success ) {
	echo json_encode( 'success', 1 );
} else {
	echo json_encode( 'failed', 1 );