If you have a VBulletin license you can download it here.

That will allow you to hide bbcodes such as [URL] from guests.

You should also get a mod to add a new group for spiders thou.

Update:

Install this to assign spiders to a usergroup:
http://www.vbulletin.org/forum/showthread.php?t=196418

E-Mails can you help to get more replies on your forum. Therefore some forum admins turn on this option by default. How would I do that?

To change all current members to this setting – AdminCP > Import & Maintenance > Execute SQL Query > Automatic Query, chose “Instant Email Notification” from the dropdown menu, Click the “Continue” button, and on the next page under Confirm Query Execution click “Continue” again.

Reminder: You should have a current backup before running queries.

To set the default for future registrations – AdminCP > vBulletin Options > User Registration Options > Default Registration Options > Automatic Thread Subscription Mode, select “Instant Email Notification” from the dropdown menu, and click “Save” at the bottom of the screen.

Source: http://www.vbulletin.com/