[Dovecot] [LMTP] sieve filter does not drop privilleges?

I have (user) sieve filter in my home dir. This filter uses "vnd.dovecot.filter" extension to call some shell scripts. These scrips creates some temporary files. Strange thing: whent sieve is called via dovecot-lda - these files are created by user "kjonca" when sieve is called via lmtp - these files are created by root. Is there any way to drop privilleges where lmtp passing messages to sieve? KJ

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