Shift Codes Borderlands 3

Question. I just redeemed 5 keys to borderlands 3 but when I enter the game and go to the mailbox to collect those 5 keys, there not there. Why is this?

Thank you.

Are you sure it was for BL3? Sounds like the code was for different game.
Check here
Also every BL3 code is posted in this topic Updated shift codes