Sieve rules

[ladas at seznam.cz]

Hi everybody.

I would like to ask about sieve rules or folders name. I created some sieve filters and spend lot of time to discover why they not work. At the end I found answer in /var/log/maillog. When the folder name contains other characters than English letters the rule not work and in log is this:
lmtpunix[21195]: autosievefolder: User info^user at domain.cz, folder domain.cz!user.info^user.logs.užitečná_slořka creation failed. Invalid mailbox name
lmtpunix[21195]: sieve runtime error for info^user at domain.cz id <20210930074534.9C6675CF4 at bm00.bm.cz>: Fileinto (logs/užitečná_slořka): Invalid mailbox name

Is it some way to solve this problem than rename folders? Thanks for any advice.

Server runs CentOS7 and last updates OS and Kolab too.
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Greetings, ladas