Advise on Performance testing of Emails

I would like some advice on how to volume test the sending of emails as part of Campaigns within CRM and Click Dimensions. Our requirement is for the ability to send up to 50,000 emails in a 24 hour period. We need to ensure that the activity on the backend CRM database as part of sending out this volume of emails, does not effect the performance of the CRM itself. However, as I understand things, these 'test emails' would also be used against out licensed quota of emails so it isn't a test we would want to repeat too many times.