Handle vacation messages properly

dovecot/sieve/before.sieve

@@ -1,10 +1,10 @@
 require ["variables", "vacation", "vnd.dovecot.extdata"];
 
-if ${extdata.reply_enabled} {
+if string :is "${extdata.reply_enabled}" "1" {
   vacation :days 1 :subject "${extdata.reply_subject}" "${extdata.reply_body}";
 }
 
-if ${extdata.forward_enabled} {
+if string :is "${extdata.forward_enabled}" "1" {
   redirect "${extdata.forward_destination}";
   keep;
 }