Your inbox, on your side.
A privacy-first email app: a messenger-style inbox, AI that triages on your own device, and post-quantum encryption. Your mail stays on your phone — not on our servers.
The idea
Ten accounts. A hundred messages a day. The inbox stopped working a long time ago.
Mostpost treats email like a conversation, not a to-do list that fills itself. People become chats. Newsletters and bots get their own quiet corner. And the AI does the sorting — on your device, where it belongs.
Conversations, not an inbox
Email that reads like messaging.
Every person is a chat thread. Replies are bubbles. The whole back-and-forth of a deal, a project, a friendship — in one calm place, instead of forty subject lines.
AI that shows its work
It triages. Then it tells you why.
Mostpost surfaces what needs you and quiets what doesn't — and every decision is something you can open and inspect. The model runs on your device or on an AI server you control. Nothing about your mail is sent to a third-party AI cloud.
Private by construction
Encryption built for the next decade.
Mostpost's end-to-end-encrypted messages use a hybrid of ML-KEM-1024 and X25519 — an attacker would have to break both, including the post-quantum half. Keys are derived from a seed that never leaves your device.
End-to-end encryption applies to Mostpost's encrypted messages. Ordinary email still travels through your provider — Mostpost is just honest about which is which.
Local-first, every account
Tasks and dates, lifted from your mail.
Mostpost spots the meeting, the deadline, the “can you send that back” — and turns them into events and tasks in a local calendar. Gmail, Outlook/Microsoft 365, Fastmail, and plain IMAP all live in one place, stored encrypted on your device.
Where your data actually goes
No mystery about what the AI sees — or what it can't.
What the AI works on
- Your own messages, on your device or on your own AI server
- To sort, summarize, and draft replies you asked for
- Never used to train generalized AI models
- Never sold, never used for ads
What stays locked to you
- Your encrypted database lives on your device
- Encryption keys derive from a seed that never leaves it
- We run no server that stores your mailbox
- Post-quantum hybrid encryption on E2EE messages
It's all written down, in plain language, in our Privacy Policy — including our adherence to Google's Limited Use requirements.
Get Mostpost
Coming to iPhone, Android, and the web.
Mostpost is in the final stretch before launch. The same app, one codebase, on every device — install it on your phone or run it as a web app on your desktop.