[Dovecot] Conf: drop duplicates as received within 60 minutes

data/conf/dovecot/dovecot.conf

@@ -453,6 +453,8 @@ plugin {
   sieve_before2 = dict:proxy::sieve_before;name=active;bindir=/var/vmail/sieve_before_bindir
   sieve_after = dict:proxy::sieve_after;name=active;bindir=/var/vmail/sieve_after_bindir
   sieve_after2 = /var/vmail/sieve/global_sieve_after.sieve
+  sieve_duplicate_default_period = 60m
+  sieve_duplicate_max_period = 7d
 
   # -- Global keys
   mail_crypt_global_private_key = </mail_crypt/ecprivkey.pem