dovecot: fix smaller config changes

data/conf/dovecot/conf.d/10-mail.conf

@@ -6,4 +6,5 @@ mail_path = ~/Maildir
 mail_index_path = /var/vmail_index/%{user}
 mail_plugins = </etc/dovecot/mail_plugins
 mail_shared_explicit_inbox = yes
+mailbox_list_storage_escape_char = "\\"
 mail_prefetch_count = 30

data/conf/dovecot/conf.d/60-sieve-pipeline.conf

@@ -85,6 +85,11 @@ sieve_vacation_default_period = 60s
 sieve_duplicate_default_period = 1m
 sieve_duplicate_max_period = 7d
 
+sieve_extensions {
+    vacation-seconds = yes
+    editheader = yes
+}
+
 # pipe sockets in /var/run/dovecot/sieve-pipe
 sieve_pipe_socket_dir = sieve-pipe