diff --git a/zmldapsync/zmldapsync.pl b/zmldapsync/zmldapsync.pl
index 15e5f6d..8a0d1e8 100644
--- a/zmldapsync/zmldapsync.pl
+++ b/zmldapsync/zmldapsync.pl
@@ -319,7 +319,7 @@ DOMAIN: foreach my $domain ( keys $conf->{domains} ) {
       foreach my $attr ( keys $conf->{domains}->{$domain}->{users}->{attr_map} ) {
 
         if ( not defined $ext_users->{$user}->{$attr} and
-            not defined $zim_users->{$user}->{$conf->{domains}->{$domain}->{users}->{attr_map}->{$attr}} ) {
+             not defined $zim_users->{$user}->{$conf->{domains}->{$domain}->{users}->{attr_map}->{$attr}} ) {
           # Attr does not exist in external LDAP and in Zimbra, no need to continue comparing them
           next;
         }
@@ -368,6 +368,7 @@ DOMAIN: foreach my $domain ( keys $conf->{domains} ) {
         $attrs .= ' ' . $conf->{domains}->{$domain}->{users}->{attr_map}->{$attr} . " " .
                   zim_attr_value( $ext_users->{$user}->{$attr} );
       }
+      $attrs .= " zimbraAuthLdapExternalDn " . zim_attr_value( $ext_users->{$user}->{dn} );
       # The password won't be used because Zimbra is set to use external LDAP/AD auth
       # But better to set it to a random value
       my $pass = $uuid->create_str;