[Mimedefang] checking sender

[cc]

Hi,

I'm using the action_replace_with_url() routine,
but I want to allow all outgoing mail (regardless
of size), but limit incoming mail.

How would I go about in checking whether the
sender is local or not?

I thought using the $ip ne 192.168.10.0/24 is
ok, but it doesn't work.

Any help appreciated