[Dovecot] Dovecot proxy hooks

[dac at getodata.ro]

I am interested in the possibility of using Dovecot IMAP/POP proxying 
capabilities to analyze emails that are passing through and possibly 
modify content on the fly. This subject has been discussed here [1] 
before.
I have tried the mail-filter plugin [2], but the hooks it uses are only 
called in a non-proxy setup.

Is there a practical way of doing this, or plans to add such a feature?

Links:
[1]: http://dovecot.org/list/dovecot/2006-February/011704.html
[2]: http://www.dovecot.org/patches/2.2/mail-filter.tar.gz