Closing accounts and reclaiming rent
Every SithBit account is a Solana account, and creating any Solana account requires a one-time SOL deposit — rent-exemption — that scales with how many bytes the account stores. It isn’t a fee: it’s a refundable deposit that sits in the account for as long as it exists, and it has nothing to do with any price or value the account might represent (a mailbox’s rent, for example, is the same regardless of how much postage it charges). Closing an account you no longer need reclaims that rent back to you. See Solana’s account model docs for the full mechanics of how the minimum balance is calculated.
| Command | Signer | What’s reclaimed |
|---|---|---|
mailbox close | Mailbox owner | The mailbox account’s rent |
mailbox close-key | Mailbox owner | The delegated encryption key account’s rent |
frombox close | Recipient (mailbox owner) | The frombox’s rent plus its remaining stamp value |
alias close | Current alias holder | The alias account’s rent |
domain close | Postmaster | The domain account’s rent, refunded to whoever paid it originally |
Note: closing drains an account’s lamports to zero, at which point Solana’s runtime deallocates it — so a closed account’s address can generally be recreated later with the matching
createcommand. The one caveat: recreating a mailbox restarts its message-id counter at zero, so any of its old, still-open message accounts (which persist independently of the mailbox itself, settled separately bymail delete) can collide with new sends until they’re cleared out. This is an availability nuisance, not a loss of funds — closing a mailbox that still has undelivered mail is worth avoiding rather than treating as harmless.