sieve setup. no svbin ?

since moving/upgrading system I've noticed I no longer get sieve script compiled, there is no dovecot.svbin created in /var/vmail/vmail1/sbt.net.au/voytek@tld.au/sieve

what am I missing, how to check ?

also, looking at sieve.log, I see a lot of

May 31 06:32:50 lda(voytek@sbt.net.au)<1234><c4aVBfI98FzSBAAAyLbbsQ>: Error: sieve: Failed to initialize script execution: Invalid postmaster_address: invalid address `root' specified for the postmaster_address setting

# grep root dovecot.conf postmaster_address = root

what should I have ?

# dovecot --version 2.3.6 (7eab80676)