bp_invites_member_invite_remove_registration_lock()

function bp_invites_member_invite_remove_registration_lock() {
	global $bp;

	if ( ! bp_invites_member_invite_invitation_page() ) {
		return;
	}

	if ( false === bp_is_active( 'invites' ) ) {
		return;
	}

	if ( ! isset( $_GET['email'] ) || ! $email = urldecode( $_GET['email'] ) ) {
		return;
	}

	// If the url takes the form register/?bp-invites=accept-member-invitation&email=username+extra%40gmail.com,
	// urldecode returns a space in place of the +. (This is not typical,
	// but we can catch it.)
	$email = str_replace( ' ', '+', $email );

	$args = array(
		'post_type'  => bp_get_invite_post_type(),
		'posts_per_page' => -1,
		'meta_query' => array(
			array(
				'key'     => '_bp_invitee_email',
				'value'   => $email,
				'compare' => '=',
			),
		),
	);

	$bp_get_invitee_email = new WP_Query( $args );

	if ( !$bp_get_invitee_email->have_posts() ) {
		bp_core_add_message( __( "We couldn't find any invitations associated with this email address.", 'buddyboss' ), 'error' );
		return;
	}

	// To support old versions of BP, we have to force the overloaded
	// site_options property in some cases
	if ( is_multisite() ) {
		$site_options = $bp->site_options;
		if ( !empty( $bp->site_options['registration'] ) && $bp->site_options['registration'] == 'blog' ) {
			$site_options['registration'] = 'all';
		} else if ( !empty( $bp->site_options['registration'] ) && $bp->site_options['registration'] == 'none' ) {
			$site_options['registration'] = 'user';
		}
		$bp->site_options = $site_options;

		add_filter( 'bp_get_signup_allowed', '__return_true' );
	} else {
		add_filter( 'option_users_can_register', '__return_true' );
	}
}