That is strange. No, we are not passing the email, but I would not expect different requirements on production than on test server and it is not required for the test server. I would not have expected an email address to be required. I can make it pass the email for the next release which will probably ship next week. I want to put out a new version of mojoPortal and both add on products because we are now using the newer versions of AjaxControlToolkit, so there will be a new release very soon.
Possibly there are configuration options on your account at Authorize.net that can be modified from their web site.