I can't see any difference between your service and others like yopmail, apart from the fact that you are able to delete the email after a set period of time sort of like Wickr. However i don't think that should be called "decentralized".

You are still the one in charge of the site, therefore it is centralized. Users have to trust you to delete their emails.

If it was truly decentralized then we don't need to worry about you intercepting emails or not deleting it.