I think we can split the inbox into multiple sections similar to the “Favorites” list:
- Challenges (marked by a rocket): Daily Challenge, Weekly Challenge, Space Race, Flight Test: BX-6 Heavy Bomber, Key Rush Test.
- Top-10 lists (marked by trophies): Top-10 reward for Daily Challenge, Weekly Challenge, Space Race, Most Active Recruit (Daily), Most Active Recruit (Weekly).
- Squadrons (marked by squadrons icon): Invitation messages that leaders of the squadrons send you, Most Active Squadron (end of day X), Most Active Squadron (Weekly), notifications of rewards when members of your squadron complete an assigned mission.
- Recruit (messages that only you receive, marked by the “squadron leader” icon): Daily stipend, Contacts, Galaxy exploration rewards, warnings that you run out of Mountable items or extra lives or special weapons, level up (advance to new tiers), congratulations messages for top-10 rewards, Medal Awarded.
I’m against requiring players to fly to a challenge planet to play a shared mission, new players won’t have keys or fuel for that (unless it is available at every star system with no extra Always-on items required, but that defeats the purpose of the challenge planet).