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.