Disable "Send Anyway" message

When you send an email from within CRM to an email address that does not exist in CRM you get the following warning:

"The following e-mail address(es) have not been located in CRM. If you want to continue to send this e-mail, click Send Anyway. If you want to correct the e-mail addresses and try again, click Send"

Does anyone know of a way to disable this warning and just send it?

Thanks.