Add default sieve_after handler

data/conf/dovecot/sieve_after

@@ -0,0 +1,12 @@
+require "fileinto";
+require "mailbox";
+require "variables";
+require "subaddress";
+require "envelope";
+
+if header :contains "X-Spam-Flag" "YES" {
+  fileinto "Junk";
+}
+if envelope :detail :matches "to" "*" {
+  fileinto :create "INBOX/${1}";
+}