Fedora 34 sendmail + macromilter error

[diethifl]

I have an issue on a new installed fedora 34 server.
Using macromilter as I used to do on CentOS 8 machines I always get the following error in /var/log/maillog:

Aug 31 18:22:25 myhostname python3[747366]: detected unhandled Python exception in '/usr/bin/macromilter'
Aug 31 18:22:25 myhostname macromilter[747366]: Traceback (most recent call last):
Aug 31 18:22:25 myhostname macromilter[747366]: File "/usr/lib64/python3.9/site-packages/Milter/init.py", line 771, in
Aug 31 18:22:25 myhostname macromilter[747366]: milter.set_body_callback(lambda ctx,chunk: ctx.getpriv().body(chunk))
Aug 31 18:22:25 myhostname macromilter[747366]: File "/usr/lib64/python3.9/site-packages/Milter/init.py", line 173, in wrapper
Aug 31 18:22:25 myhostname macromilter[747366]: rc = func(self,*args)
Aug 31 18:22:25 myhostname macromilter[747366]: File "/usr/bin/macromilter", line 209, in body
Aug 31 18:22:25 myhostname macromilter[747366]: self.messageToParse.write(chunk)
Aug 31 18:22:25 myhostname macromilter[747366]: ValueError: I/O operation on closed file.
Aug 31 18:22:25 myhostname python3[747366]: MacroMilter: milter claimed not to reply in state 9 but did anyway 3

Until now I was unable to fix this problem.
Hope someone can fix this.

BR,
Dieter