UserModel::isEmail

public function isEmail(): bool
{
	if ($this->isEmail === null)
	{
		$this->isEmail = false;

		$user = UserTable::getList([
			'select' => ['EXTERNAL_AUTH_ID'],
			'filter' => [
				'=ID' => $this->userId
			],
			'limit' => 1
		])->fetch();

		if (
			$user
			&& $user['EXTERNAL_AUTH_ID'] === 'email'
		)
		{
			$this->isEmail = true;
		}
	}
	return $this->isEmail;
}