You should probably log a support ticket for this, but I am not too optimistic...
If you are using SFDC or MS Dynamics, in Sales Insight, you can retrieve the web copy of the emails that were sent. But you need to give a try, because I am not 100% sure that it will give you the historical version of the email.
Surely (hopefully) someone has a test version that was sent around for approvals (possibly?) One thing I like about using gmail at our office is that more email is archived than deleted and I can generally find anything that may have been 'lost' elsewhere... best of luck.