Letterslot

Development milestones.

What’s done, what we’re working on, and what comes next.

  1. Done

    Native Mac and iPhone foundation

    Shared Swift core, native navigation, independent Mac compose windows and versioned on-device storage.

  2. Done

    Core mail tools

    Rich text, attachments, message source, flags, nested labels and Mac S/MIME signing and verification foundations. Tested with synthetic mail.

  3. Working on this now

    Everyday mail workflow

    Direct IMAP and SMTP, account aliases, signatures per sending address, cleaner Settings and proper desktop text controls.

    Also in progress: on-device Screening assistance, local text and vector search, provider search, and recipient suggestions from correspondence.

  4. Upcoming

    Google and Microsoft approvals

    OAuth client setup, provider verification and the approvals needed to distribute account connections. Development-account sign-in and public approval are separate steps.

  5. Upcoming

    Fastmail OAuth

    Client registration, consent, refresh-token handling and real-account testing. App-password IMAP remains available where the account allows it.

  6. Upcoming

    Real-mailbox reliability

    Test all five providers with full history, Sent mail, server-side filing, reconnects and external changes. Measure search and reading performance on large mailboxes.

  7. Upcoming

    iCloud sync

    Sync Letterslot settings, sender decisions, aliases and signatures using storage you control. Test migration, offline changes and conflicts across devices.

  8. Upcoming

    Background notifications and beta testing

    APNs provisioning, device registration, Focus behaviour, accessibility and repeated locked-device testing before a public beta.

Account connections today

IMAP is the mail transport. Use OAuth or an app password where the provider permits it; using IMAP does not bypass a provider’s sign-in requirements. Live provider testing and approvals are still in progress.

There is no public download or release date yet. Completed milestones describe development builds, not production acceptance against every provider.

Updated 19 October 2026