no i mean this:
my first versions of the forwarding plugin had forwarding and delete option. At this time ispconfig didn't had any forwarding options.
in the later version ispconfig implemented a forwarding option, but without the delete option. This is used now, so that people can easily change the forward address in roundcube and/or ispconfig.
my first versions worked without a doubt, but i always had to write a custom script to insert into custom mailfilter