[exim] Attachment handling

Hi

I know that exim itself does not care about attachments.
However pipe delivery agents can.

I need to fulfill the following:
1) I need to deliver a mail for a user, but I need to cut every attachment,
which is not of a certain type. Every allowed attachment should be kept and
delivered with the message.
2) I need to deliver a mail for a user, WILL ALL ATTACHMENTS, but only if
there is at least one attachment of a certain type.

Can someone tell me, which delivery agent you use or maybe give me a hint,
which one could be suited best...

Regards,
Steffen