Yeah. The mailbox uses Exchange slots for returned items until they're claimed.
STO is about my Liberated Borg Federation Captain with his Breen 1st Officer, Jem'Hadar Tactical Officer, Liberated Borg Engineering Officer, Android Ops Officer, Photonic Science Officer, Gorn Science Officer, and Reman Medical Officer jumping into their Jem'Hadar Carrier and flying off to do missions for the new Romulan Empire. But for some players allowing a T5 Connie to be used breaks the canon in the game.
#1 yet another recent nerf limitation
#2 yet another game mechanic that is not explained ANYWHERE in the game
#3 yet another no logic (from player POV) limitation that confuses newer players
#4 yet another important "feature" that is impossible to keep track of
#.... well you get the picture.
If your post is anything like, "I have a sandwich so you can't be starving" it's time to rethink posting. ~thlaylierah
So realistically, you only need to have the exact number of doffs that you need. ~leadme2kirk