First of all: great plugin! :-)
When one has more than 20 domains mapped, not all are shown due to the lack of pagination. In the file domain_mapping.php (v0.5.2) I removed the limit from the next query (as a quick fix):
$rows = $wpdb->get_results( "SELECT * FROM {$wpdb->dmtable} ORDER BY id DESC LIMIT 0,20" );
This query then becomes:
$rows = $wpdb->get_results( "SELECT * FROM {$wpdb->dmtable} ORDER BY id DESC");
Cheers!
Laurens Meurs (Rotterdam, the Netherlands)