add antispam support using imap sieve

confd/templates/90-sieve.conf.tmpl

@@ -0,0 +1,22 @@
+plugin {
+  sieve_plugins = {{ if eq (getv "/sieve/enable") "yes" }}sieve_imapsieve{{ if eq (getv "/antispam/enable") "yes" }} sieve_extprograms{{ end }}{{ end }}
+
+  sieve_before = /etc/dovecot/sieve/before
+  sieve_after = /etc/dovecot/sieve/after
+
+  {{ if eq (getv "/antispam/enable") "yes" }}
+  sieve_global_extensions = +vnd.dovecot.pipe +vnd.dovecot.environment
+  sieve_pipe_bin_dir = /etc/dovecot/sieve
+
+  # From elsewhere to Spam folder
+  imapsieve_mailbox1_name = Junk
+  imapsieve_mailbox1_causes = COPY
+  imapsieve_mailbox1_before = file:/etc/dovecot/sieve/report-spam.sieve
+
+  # From Spam folder to elsewhere
+  imapsieve_mailbox2_name = *
+  imapsieve_mailbox2_from = Junk
+  imapsieve_mailbox2_causes = COPY
+  imapsieve_mailbox2_before = file:/etc/dovecot/sieve/report-ham.sieve
+  {{ end }}
+}