Zero Invoice - Domains

Hi

Now I am sure I can write a hook which would mitigate this problem, but I thought I would check there isn't a better solution available.

We have a problem where when a client transfers a domain to us (mostly .uk through Nominet) and we set the domain to active, the next time the cron job runs the client will receive an email with an invoice for £0.00 for the domain.

I was wondering if there is a way to stop WHMCS generating invoices that are for nothing (or at least stopping them being emailed?

Many Thanks

Leo