diff --git a/config.inc.php b/config.inc.php
index b19e6309..3878a589 100644
--- a/config.inc.php
+++ b/config.inc.php
@@ -322,6 +322,9 @@ $CONF['show_custom_colors']=array("lightgreen","lightblue");
 // $CONF['create_mailbox_subdirs']=array('Spam');
 // $CONF['create_mailbox_subdirs_host']='localhost';
 //
+// Specify '' for Dovecot and 'INBOX.' for Courier.
+$CONF['create_mailbox_subdirs_prefix']='';
+//
 // Normally, the TCP port number does not have to be specified.
 // $CONF['create_mailbox_subdirs_hostport']=143;
 //
diff --git a/functions.inc.php b/functions.inc.php
index 26c8e16e..69399931 100644
--- a/functions.inc.php
+++ b/functions.inc.php
@@ -1915,6 +1915,7 @@ function create_mailbox_subfolders($login,$cleartext_password)
    }
 
    $s_host=$CONF['create_mailbox_subdirs_host'];
+   $s_prefix=$CONF['create_mailbox_subdirs_prefix'];
    $s_options='';
    $s_port='';
 
@@ -1957,7 +1958,7 @@ function create_mailbox_subfolders($login,$cleartext_password)
 
    foreach($CONF['create_mailbox_subdirs'] as $f)
    {
-      $f='{'.$s_host.'}INBOX.'.$f;
+      $f='{'.$s_host.'}'.$s_prefix.$f;
       $res=imap_createmailbox($i,$f);
       if (!$res) {
          @imap_close($i);