Add stamps

sithbit frombox stamp <from> [to_address] \
  [--keypair <keypair>] \
  [--stamps <count>] \
  [--skip-preflight]

to_address defaults to your own address; --stamps defaults to 1. For example, topping up a sender’s frombox by 10 stamps:

sithbit frombox stamp jane_doe@sithbit.com --stamps 10

Each stamp purchase pays the protocol’s flat per-stamp fee (waived when the payer is the mailbox owner themselves — see Economics for the exact amount). Sending one email always burns exactly one stamp, regardless of the frombox’s stamp price; the lamports transferred to the recipient when a stamp is burned are the frombox’s remaining balance divided by its remaining stamp count, so the per-stamp price you set is really “the value backing each stamp,” not a per-send fee charged separately.

When a frombox is no longer needed, see Appendix: Closing accounts to close it and reclaim its rent and remaining stamp value.