Validate Sitefinity Email Campaign Subscriber List

Is there a tool that will validate emails when imported using an Excel spreadsheet, for example? Ideally it would be nice if Sitefinity could validate emails on Import so that no bad emails make it to the system.  Overall it would be nice to have a tool to assist with email cleaning.  

In my experience sending a malformed email to a Sitefinity Campaign is nuclear.  It's the definition of an application bombing, however it has no problem allowing the email into the database.