How pay-to-send works
The toll that makes spam expensive instead of free — and pays you.
Email spam exists because sending is free. MailGate puts a price on reaching an inbox that hasn't approved you. That price is the toll.
The rule, in order
When mail arrives for you, MailGate checks the sender against your lists, in this order:
- On your whitelist (approved senders / contacts)? → delivered straight to your inbox, free. No toll.
- On your blacklist? → rejected before it's ever stored. You never see it.
- Unknown sender? → the sender is asked to pay your toll before the message lands in your inbox.
So your real contacts never pay anything, blocked senders can't get through, and strangers have to put a little money behind wanting to reach you.
How a sender pays
An unknown sender can pay the toll two ways:
- Card via Stripe — pay with a regular credit/debit card. No crypto needed.
- Stablecoin USDC — pay directly with a stablecoin from a Sui wallet.
Either way, once payment is confirmed the message is delivered to your inbox and the toll credits to your account balance.
Card payments take a few seconds to reconcile (usually under 10 seconds, sometimes longer under load). A toll that shows as "pending" for a moment is normal — it's waiting for confirmation, not stuck.
You earn from your inbox
Tolls people pay to reach you accrue to your on-chain balance. You can see them add up on the Balance settings page and in your analytics (earned vs. spent, traffic, money flow).
Withdrawing earned tolls isn't available in the app yet. You can see your balance grow, but moving the money out isn't wired up for users yet. See Withdrawing tolls.
What this does and doesn't catch
The gate is economic plus your own lists. It is very effective against bulk spam, for which "free" was the whole model.
It is not a content filter:
- There's no machine-learning spam classifier. Newsletters and marketing mail from a sender you've whitelisted will land in your inbox — because you approved them.
- There's no phishing/impersonation detector and no sender-spoofing warnings yet.
- Sender-authentication records (the technical anti-spoofing checks) are read but not used to block mail today.
In short: the toll stops strangers cheaply blasting you; your whitelist/blacklist is how you handle the rest.