Your mail, on your computer.
Halcyon is a mail client for Windows 11, built to feel like macOS Mail: three panes, no ribbon, no inspector, nothing asking to be noticed.
It works with the account you already have — Gmail, iCloud, Yahoo, or any IMAP server. There is no Halcyon account, no server of ours between you and your provider, and no analytics of any kind.
A Gmail account signs in through Google, in your own browser. Halcyon asks Google for access to your mail and nothing else, and uses it only to do what a mail client does: download your mail to your computer so you can read and search it, send what you write, and organise it when you ask. None of it is sent to us — the privacy policy has the details.
Reads offline
Mail is downloaded and indexed locally, so reading and search work with no connection.
Search that means something
Full text across every account, over a hundred thousand messages, without waiting.
Undo
Archive, move, delete, flag, run rules — Ctrl + Z puts it back. Send has a hold you can cancel.
You can leave with it
Import from Thunderbird, Outlook and mbox. Export to mbox or a folder of .eml files.
What it deliberately does not do
- No telemetry, no analytics, no crash uploads, no “anonymous usage data”.
- No account to create, no subscription, no cloud service.
- No AI features reading your mail.
The privacy policy says exactly what connects where, and the source code is published so that anyone can check it.
Getting it
Halcyon is not yet released. When it is, it will be on the Microsoft Store and as a download from the releases page.
Contact
Questions or problems: vnikie1@gmail.com.
Security problems: please follow the disclosure process.