Why Postel works this way

Every mail app makes one decision before all the others: does your mail pass through the maker’s servers, or doesn’t it? Everything else — privacy, speed, what the app can promise you — follows from that. Postel made the decision once, and made it absolute: your mail travels between your Mac and Gmail, and nowhere else.

The architecture

Postel talks to Gmail directly from your Mac, over Google’s own API. There is no BNFY mail server: nothing to sync your messages to, nothing to index them on, nothing to breach. What Postel knows about your mail lives in a local cache on your Mac, protected by your Mac account and FileVault. When you quit Postel, no copy of your inbox is working for us somewhere else.

What other apps do — in their own words

This isn’t speculation; each of these is the vendor’s own documentation, linked so you can read it whole.

Microsoft’s new Outlook syncs a connected Gmail account to Microsoft’s data centers — in their words, a copy of your email, calendar, and contacts is synchronized between your provider and Microsoft.

Spark stores part of each message on its servers to deliver notifications, and its Send Later and Templates run server-side: schedule a message for noon tomorrow and Spark holds it, encrypted, on their infrastructure until then.

Shortwave keeps synced mail in its cloud infrastructure and processes it there for search and its AI assistant, with named sub-processors.

All three describe encryption and careful engineering, and there is no reason to doubt them. The difference is architectural: a well-guarded copy of your mail on someone else’s servers is still a copy of your mail on someone else’s servers.

What the architecture buys you

Because there is no server in the middle, there is no copy of your mail for a subpoena to find at BNFY, none for a breach to leak, and no quiet accumulation of your correspondence under someone else’s roof. Tracking pixels are blocked on your Mac before they load. Postel adds no read receipts to your outgoing mail. When you revoke Postel’s access in your Google account, the relationship is over — there is no second copy to chase.

What it costs — honestly

The same choice has consequences, and you should know them. Postel’s Snooze and Send Later run on your Mac: overdue snoozes return and scheduled mail goes out the next time Postel is running and online, not from a server while your Mac sleeps. There is no web version, because there is no server to serve one. Postel thinks that trade is right — the features you gain from a server in the middle are paid for with a copy of your mail — but it is a trade, and Postel would rather name it than hide it.

See everything Postel does, or read the privacy policy in plain language.