Quarantine mail by combination of address class and MIME type

[Philip Garrett]

I have a special-purpose Postfix 2.6 server that is part of a content 
conversion system.  I would like to quarantine any outbound mail that hasn't 
been transformed properly. I'd also like to quarantine relay mail that hasn't 
gone through the reciprocal transformation.

I can hold the mail using mime_header_checks, but this would apply to both 
outbound (default domain class) and inbound (relay domain class).  What I 
really want to do is something like this:

    if DEFAULT_DOMAIN_CLASS
    if /^Content-Type:/
    !/^Content-Type:\s*application\/x-my-custom-format/
        HOLD was not encoded
    endif
    endif

    if RELAY_DOMAIN_CLASS
    if /^Content-Type:/
    /^Content-Type:\s*application\/x-my-custom-format/
        HOLD was not decoded
    endif
    endif

Is there a way to accomplish that?

Thanks,
Philip