Probably I'm doing something stupidly wrong.
I have dovecot 1.2.7 and sieve 0.1.13.
I have a sieve script starting with
# <some comment>
require ["vacation", "date", "relational"];
I get
main_script: line 2: error: require command: unknown Sieve capability
'date'.
Just to make sure I haven't messed up the dovecot package:
$ strings /usr/pkg/lib/dovecot/lda/lib90_sieve_plugin.a | fgrep date_extension
date_extension
date_extension
date_extension
date_extension
date_extension
What's going on? It's probably some totally stupid typo on my side.