Thank you for the help! I will try this tomorrow. I am used to working with java so I am not to good with PhP. If I can’t get it to work I’ll email you though!

Dear Adian, you need to consult the developer for that. It requires good knowledge in programming to handle the case. The developer need to check the

1. $email domain contains your domain then allow the reg
2. Otherwise don't allow it.
3. Email can be obtained in same function by $email = input('email'); and then the rest condition need to be written.

In the end it should appear like this

function restrict_usernames($name, $type, $params) {
		if($params['action'] == 'user/register') {
				$email = input('email');
				if($email does not contain your domain then do not allow it) {
				//if(!str_ends_with('@yourdomain.com', $email){
								header('Content-Type: application/json');
								echo json_encode(array(
										'dataerr' => ossn_print('restrictusername:error'),
								));
								exit();
				}
		}
}

You may contact me at [email protected] for custom work at additional cost.

I now have `function restrict_usernames($name, $type, $params) {
if($params['action'] == 'user/register') {
$username = strtolower(input('username'));

			$component = new OssnComponents();
			$list      = $component->getSettings('RestrictUsernames');
			if($list && isset($list->list) && !empty($list->list)) {
					$usernames = explode(PHP_EOL, $list->list);
					$usernames = array_map('strtolower', $usernames);
					$usernames = array_map('trim', $usernames);
					$email = input('email');
							header('Content-Type: application/json');
							echo json_encode(array(
									'dataerr' => ossn_print('restrictusername:error'),
							));
							exit();
					}
			}
	}`

Will it only restrict the end of the email like @email.com?

Like this? if(in_array($email = input('email');)) {

You can see https://www.opensource-socialnetwork.org/component/view/5891/restrict-usernames and clone component it does same thing but you need to adjust https://github.com/opensource-socialnetwork/RestrictUsernames/blob/main/ossn_com.php#L31

$email = input('email');