The apsfilter license is a combination of the GNU GPL and postcardware:
"You are permitted to use the apsfilter package in the terms of the GNU
General Public License. If you use apsfilter for business or home
purposes, then please send me a postcard. This product is otherwise free
Is this allowed? apsfilterconfig terminates if the user does not accept
the license. I am under the impression that the GNU GPL does not permit
these kind of additions, that is, requiring physical goods to be sent to
the software author(s).
If someone uses code from apsfilter in GPL'd programs, would the users
of said programs have to send postcards to Andreas Klemm?