You have an issue with MTG Studio or simply a very cool feature suggestion.
1. Read the forum http://www.mtgstudio.com first. You can use the Search to check if someone else is not thinking alike and already asked a similar question.
2. Post your topic in the forum.
The forums are more commonly read and replied to compared to an email sent to support@mtgstudio.com.
And forums are read not only by the developers but also by other MTG Studio users.
I (the MTG Studio developer) read all Forum and Feedback (from http://mtgstudio.uservoice.com) on a daily basis with my Google Reader. It is simply faster then reading my mailbox.
3. If you really like to send some private data like (a test deck or collection file) or would like your registration key restored - send an email to support@mtgstudio.com.