Dovecot no logs by sieve user script [SOLVED]

[Christian Wolf]

Dear mailing list,

I have to admit, I was mislead: I thought that some messages should be 
logged anyway. But in fact sieve only logs errors by default.

So I had to introduce a intended error in my sieve script, trigger it by 
sending a mail and voi-là: the log got its error messages.

So this topic can be seen as solved.

Thanks anyways
Christian