This feature wont be in core. Anyway I would recommend you this plugin from @SvePu http://community.mybb.com/mods.php?action=view&pid=334
@Supryk - thank you for your idea. It is already implemented by @SvePu and it is ready for v1.9.10
(2015-11-18, 12:44 PM)Supryk Wrote: I still thing that method to delete or not delete file from ftp to keep DB data is no not needed
look in to hello.php plugin
@Supryk - thank you for your idea. It is already implemented by @SvePu and it is ready for v1.9.10

[MyBB 1.8 Czech translation] [MyBB 1.8 plugins]: Prune old PMs + optimize DB plugin --- Thank you/like system