Deliver to a specific version via Inbound Mail service
There is an easier way to do this than writing code that routes between different versions using URLFetch.
If you have a large body of code that is email oriented and you need to have a development version,
simply use one of your ten applications as the development application (version).
This allows you to do things like have test-specific entities in the development application Datastore and you can
test as much as you want running on appengine live.
The only constraints are:

because the application has a different name, for email sending from the application, you either need to send from your gmail account or have a
configuration that switches the application name
sending test email to the application will have a slightly different email address (not a big issue I think)
keep an app.yaml with a different application name
you burn another one of your ten possible apps

Most RCS will allow you to have the same project checked out into different directories. Once you are ready for launch
(all development code is committed and testing done), update the 'production' directory (except for app.yaml) and then deploy.
I have an app that services inbound mail and I have deployed a new development version to Google App Engine. The default is currently set to the previous version.
Is there a way to specify that inbound mail should be delivered to a particular version?
This is well documented using URLs but I can't find any reference to version support in the inbound mail service...