--- a/src/lib/confdef.pm
+++ b/src/lib/confdef.pm
@@ -728,9 +728,10 @@
     },
     {
         name   => 'db_port',
-        default => '3306',
+        default => undef,
         query  => 'The database port',
         file   => 'sympa.conf',
+        optional => '1',
     },
     {
         name   => 'db_user',
