kopano-spamd: HAM logic is blocked by "header_tag = X-Spam-Flag"

[PRO123]

I got kopano-spamd after some back & forth now after these recommendations to run:
https://forum.kopano.io/topic/2027/kopano-spamd-error-permissionerror-errno-1-operation-not-permitted/48

But HAM will only be recognized if there is no X-Spam-Flag Header in the mail when moving HAM from the Junk-Folder back to the Inbox. Now, of course, there are only such mails (in our inbox), because they were tagged via spamassassin & amavis in order to be moved into junk at all. I.e. I can’t send any mails via spamassassin & amavis that were originally detected as spam to the HAM learning logic.

In my opinion the program logic is not correct or I understand something fundamentally wrong?

P.S.:

• The kopano-spamd docu is unfortunately still a bit confusing & incomplete.

• I had to create the config file /etc/kopano/spamd.cfg (on a Univention UCS 4.3 system) definitely, before the kopano-spamd service never ran correctly, especially no logging, although the default values should be the same except for the above adjustments (run_as_group = amavis).

TIA, Robert