[peterska2]

Assuming you have set your config.php to allow you to run SQL queries from the control panel.....

Go to Maintanence > Execute SQL Query.

Select the following from the drop down list, pressing continue beteen each one till you return to the same screen.

No - Recieve Admin Emails
No - Send Notification Email When A Private Message Is Recieved
Subscribe with no notification

Then in vBulletin Options > vBulletin Options > Email Options

Set everything on this page to NO

If you don't want welcome emails go to vBulletin Options > User Registration Options

Send Welcome Email - No
Default Registration Options
Receive Admin Emails - No
Send Notification Email When a Private Message is Received - No
Automatic Thread Subscription - Do not subscribe

That should stop quite a lot of them, but I don't think it will affect anything that they have already got in their subscribed folders. You will need a manual query for that, so I will have to leave that bit for someone else to do.