diff --git a/mailserver.env b/mailserver.env
index 0d00de0a..e796aef8 100644
--- a/mailserver.env
+++ b/mailserver.env
@@ -510,6 +510,14 @@ DOVECOT_MAILBOX_FORMAT=maildir
 # https://wiki.dovecot.org/AuthDatabase/LDAP/AuthBinds
 DOVECOT_AUTH_BIND=
 
+# empty => separator of namespaces is backend-dependent
+# typical namespace separator is slash `/`
+DOVECOT_NAMESPACE_SEPARATOR=
+
+# 0 => inbox sharing is disabled
+# 1 => inbox sharing is enabled
+DOVECOT_ENABLE_INBOX_SHARING=0
+
 # -----------------------------------------------
 # --- Postgrey Section --------------------------
 # -----------------------------------------------