All users who have forum premium upgrade in their account now have the following:
(Click the ***'s for more information)

*** Rejoin deleted PMs. NEW!
*** Create detailed PM conversation filters. Fixed.
*** Create detailed PM conversation prefixes. Fixed.
*** Create detailed PM participant groups. NEW!
*** Create detailed PM auto response messages when you're away. Fixed.

Forum premium upgrade is free for those who participate in our sale promotion:
https://www.ecocitycraft.com/forum/threads/.175968/

PS: Finally you can rejoin that PM you deleted long ago that you suddenly really need