[Mimedefang] Header extraction question

[NFN Smith]

Is there a way of extracting headers of a message in mimedefang?

What's up is that for messages submitted by my local users 
(authenticated connections), I'd like to get to the contents of 
User-Agent and X-Mailer headers.

Initially I want to just do logging for some statistical analysis, but 
in the longer run, if it's possible, I'd like to be able to force 
rejections of exchanges coming from users that have unapproved mailers 
(e.g., old versions that are no longer supported by the developer).

Is there a way of doing this?

Smith