The rewards from the reclamation rig that are send to your mailbox won’t open and would just gray-out and remain in your inventory.
Heya,
This is a known issue that is being worked on. For now, make sure that you have inventory space before completing the events, so you receive the chest directly. The ones that are mailed to you (inventory full), cannot be opened. Sorry for the confusion caused.
Have a few seconds to spare? Let me know how I’m doing!