> some Mailinglists are using headers like
>
> List-Post: <mailto:
postfi...@postfix.org>
>
>
> How can i use filters with those headers?
As far as I am aware, the only line in the (otherwise normally hidden)
headers that Gmail will recognize in searches and filters, is the
List-ID: line. It seems a Gmail search (which is used by filters)
doesn't look in the hidden header lines, except List-ID:. That one
was added as a special case, long ago.
If you need to add another, you could try positing it as a suggestion
to the Gmail folks.
Andy