This only works when ``recent_days`` is configured to be large enough so the changes file still contains at least one change for each page in the namespace that has been changed since the last time subscriptions were sent. This could be a problem with namespace subscriptions for namespaces that are infrequently visited in a wiki that has lots of edits. Maybe we should scan the whole namespace for files that were modified more recently than ``$lastupdate`` when ``$lastupdate`` is smaller than ``time() - $conf['recent_days']*86400``?