[Exim] Auto bounce under some conditions

To battle against virus, it's considered that add some new facility to current Exim-based email system.: when exim recevied an email message which contains particular type of attachment files, it reject message and bounce a message to inform both sender and recevier.

The exim is v 4.34 with exiscan-acl patch. Some snippets from exim.conf is:
...
acl_smtp_data                 = acl_check_data
...
acl_check_data:
    discard message       = This is LoveGate.x virus.
            condition     = ${lookup{$h_subject:}lsearch{/etc/exim/virus/lovegate.x.title}{$value}}

    deny    message       = The server rejected attachment with extension: $found_extension
            demime        = exe:com:vbs:bat:pif:scr:zip
...


The problem is when "deny", how to auto-bounce a message to tell the sender that the attachment type is forbided and tell the receiver that some user has ever sent an message with an forbied attachment type?

Thanks
/Hunte