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Introduction

Spam isn’t a filtering problem. It’s an economics problem, and email has never fixed it. Sending mail costs a spammer essentially nothing, so even a 1-in-12,500,000 response rate still nets about $7,000 USD/day at scale. Multiply that incentive across the internet and you get the numbers today: an estimated 362 billion emails sent daily, with 45-60% of it spam. No amount of machine-learning spam detection can win that fight permanently — filters treat the symptom, and the number of spam emails keeps climbing precisely because the incentive to send it was never touched.

Worse, fighting spam with filters costs you twice over. Your provider has to open and read every message to classify it, so you’re trusting a third party with your mail’s contents in exchange for a losing battle. And that provider usually also owns the domain your address lives on — your identity on the internet is rented, not owned, and it stops existing the moment they decide it should.

The mail program fixes the actual incentive: it charges the sender, not the recipient, and lets you set the price.

Blockchain Email

In the earliest days of U.S. postage, letters were paid for by the recipient, and the system was so inefficient it collapsed under its own volume. Email never got past that stage — you still bear the cost of your inbox, either directly through a subscription or indirectly through the ads and data-mining that fund “free” accounts. Stamps fixed postal mail over a century ago by putting the cost on the sender instead. SithBit does the same for email, and takes it a step further: instead of one central post office setting one universal price, every mailbox owner sets their own price, per sender if they want to.

That single change is what makes spam uneconomical rather than merely harder to get away with:

  • You price out spam, not guess at it. Every message to your mailbox costs the sender real SOL — a stranger has to pay to reach you (new mailboxes default to 1 SOL/message), and you can raise, lower, or waive that price per sender at any time. Spam has to actually be profitable after your price, not just after a filter’s guess.
  • You get paid for your own attention. Postage from strangers accrues directly to your wallet — you’re compensated for the inbox space you’re already defending, instead of paying a provider or letting them monetize your data instead.
  • Known senders cost you nothing extra. Each correspondent gets their own prepaid postage balance for mail to you (a “frombox” — see Fromboxes). Allow-listing someone just means funding theirs yourself, and that value round-trips back to you as their mail arrives, so recognizing someone you trust is free beyond ordinary transaction fees.
  • You only ever pay for mail you mean to send. As a sender, there’s no subscription and no ad-supported inbox trade-off — postage is the price of the message you chose to send, nothing more.
  • Your address is yours. It’s tied to your wallet, not to a domain someone else controls, so nobody can revoke it out from under you. It’s not permanently tied to any one domain either — you can move it to a different domain at any time, keeping your wallet, mail history, and identity intact.

See Economics for the full lamport-by-lamport ledger of who pays and who collects at every step.

Decentralized Email

Pricing solves the incentive; storage solves the trust problem. This system uses the Interplanetary File System (IPFS) to store mail bodies, encrypted by the sender, so no central authority ever holds your messages in the clear — see IPFS storage: benefits to users for what that means for you, and where to go for the IPFS project itself. Taken together, it’s possible to send email between two addresses using only the blockchain for transactions and IPFS for storage — bypassing the internet’s traditional SMTP relay infrastructure entirely.

Anyone With a Domain Can Run One

SithBit isn’t a single proprietary email service with one company behind it — it’s a protocol. Running the mail servers (sithbitd, the combined SMTP/IMAP/POP daemon — see Running a mail server) takes no special permission: authorize your own domain on-chain, point its MX record at your server, and you’re a first-class mail operator on the same footing as anyone else on the network.

Hosting isn’t charity, either — it’s the third profitable role in the system, alongside senders and recipients:

  • You earn a cut of every message you relay. For each mail settled on a mailbox under your domain, your operator wallet collects a share of that message’s postage — 10% by protocol default (see Economics for the exact split) — so the more mail your domain carries, the more it earns, turning what used to be a pure hosting cost into a revenue stream that can offset it.
  • The barrier to entry is a small, flat, one-time fee, not a gatekeeper’s approval — authorizing a domain costs 0.01 SOL paid on-chain once, verified against your domain’s DNS TXT record. No central provider decides who’s allowed to run a mail server.
  • You’re never locked into someone else’s infrastructure. Because routing and pricing live on-chain rather than inside one company’s servers, you can self-host a domain you already own instead of renting identities out to users the way traditional email providers do.

Only on Solana

Pricing every message individually only works if the settlement layer can keep up. To support even a small fraction of global email traffic, a blockchain-based mail system needs to clear millions of transactions per second — throughput only the Solana blockchain provides today.

Priced in SOL — No New Token to Trust

If you’ve been anywhere near crypto, you already know the pattern: a project launches its own token, and your upside depends on a team you don’t control — one that can pre-mine a chunk for themselves, unlock more supply later, or simply walk away with the liquidity. SithBit doesn’t ask you to take that bet. There is no SithBit token. Postage, stamps, and every payout described above move in native SOL — the same SOL you already hold to pay transaction fees on Solana for anything else.

That means no mint anyone controls, no allocation for insiders to dump, and nothing to “rug.” Sending and receiving mail never requires acquiring, wrapping, or swapping into some other asset first — if you hold SOL, you already hold everything the protocol needs from you.