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.
Theres plans in the works to integrate into blockchain, and I can understand your concerns. This is beta v0.1, and frankly no one says anyone has to use it. Just trying to help others not get spam on basic sites like forums etc. I know I will use it for sure glad I took the time to make it work to my privacy standard.
So if your worried/paranoid don't use it for any serious sh**, keep it basic. ....Nuff said....