Love the idea.
However, what happens if the anonymous email forwarding service disappears (e.g. shuts down)? Does it mean users won't be able to access any online service they signed up for with an anonymous email address?
Thanks, this will always be a concern for these types of services. I will be keeping this service running indefinitely as I use it myself everyday along with friends and family. I originally created the service to solve my own problem.
The best way to mitigate against the risk of a service shutting down is to use your own domain name. That way, by simply changing your MX records to another email provider, you can continue to receive emails as normal.
You could reverse engineer their app and see if it matches your implementation. Super easy if it's html app. Not too hard if objective-c since it is very verbose, even with symbols stripped.