How to set response format for errors coming out of apigee router

[vednath_pittala]

We have a set of virtual host aliases defined for a given organization. When a request is made with the right virtual host and by the use of any interceptor if the host name in the header is changed to something else then Apigee sends out a response in the format below

{ "fault": { "faultstring": "Classification failed for host: google.com url: /", "detail": { "code": "CLASSIFICATION_FAILED" } } }

If i wanted to standardize this error format to say something like "error":"The hostname doesnt match with virtual hosts configured" how would i be able to do that?

I noticed that these errors are not captured on either message processor or router logs and having a default error proxy on a given organization doesnt help me either

Thanks,

Vednath