This is the expected (and unfortunately wildly unpopular) results.
You will get a separate email for each signing key that is applied to each COD file in your application. Due to the nature of how OTA deployment works with the BlackBerry Device software, large applications can be split up into multiple 64Kb COD files (that are assembled during install). As a result, if you have a large application (e.g. 2Mb+), you can get many emails.
Although the flood of emails may seem overwhelming, there is merit in receiving notifications when your signing keys are being used. It does provide a way of monitoring and responding to unauthorized usage.
I just spoke with the code signing guys and they are working on a solution to make this better. You may have noticed that the PlayBook signing process does not invoke these emails. The best way to manage this is in the meantime is to either setup an email filter, or have an alternate email address assigned to your signing keys (so that these notifications go there and not flood your inbox).
Note - new code signing keys are also issued using the same email addrress, so you don't want to block this address entirely.
