[Exim] Filtering messages on server during delivery

Hi,

I have Exim 4 + Courier IMAP 2.2.0 configuration featuring virtual domains. All user profiles
are stored in MySql. I want to allow my users to create filters for delivering mails into
specific IMAP folders centraly on server rather than localy in IMAP clients.

I've read about Exim filters, but as I understand thay are used mainly for routing. I've also
took a look at maildrop but it does not support MySql.

Have anyone implemented something like that? Can it be done using Exim filters or what
filtering utility can you suggest to easily integrate it in Exim? May be some one would be
kind enough to share his configuration?

This is how my final transport looks like:

virtual_local_delivery:
driver = appendfile
create_directory
delivery_date_add
directory = "${lookup mysql{SELECT maildir FROM users WHERE id = '${local_part}@${domain}';}}"
envelope_to_add
group = mail
maildir_format
maildir_tag = ,S=$message_size
mode = 0600
quota = ${lookup mysql{SELECT quota FROM users WHERE id = '${local_part}@${domain}';}}
quota_size_regex = ,S=(\d+)
quota_warn_message = "bla-bla-bla"
quota_warn_threshold = 80%
return_path_add
user = mailnull

Regards, Andrey Novikov