Open source and in active development

Every email is something to do, hand over or know.

tresso is an email client and calendar for all your accounts that turns reading into deciding. Each message leaves your inbox as a todo, a handover to someone else, or a line in your daily brief.

Run it yourselfSee all features
Unified Inbox3 accounts
  • Lena Hartmann09:12Contract renewal: signature needed by FridayDoTodo, due Fri
  • Support queue08:47Customer cannot export last month’s invoicesHand overTo Sam, due Wed
  • Product Weekly07:30What shipped this weekKnowIn your brief
  • Pieter de VriesYesterdayCould you review the Q3 deck before Thursday?DoTodo, due Thu
  • Building managementYesterdayElevator maintenance on Thursday morningKnowIn your brief
Settle each email with one keyDHK

The idea

One T, three ways out.

The tresso mark is a T made of three bars. Each bar is one way an email can leave your inbox. Nothing just sits there.

  1. Do
    What happens
    It becomes a todo, linked to the email, with a due date when there is one.
    Done when
    The todo is completed. The email archives itself.
  2. Hand over
    What happens
    It goes to someone else with a note and a due date, and waits in Waiting on.
    Done when
    They finish it. Until then, tresso keeps track and nudges.
  3. Know
    What happens
    It lands in your daily brief, together with everything else worth knowing.
    Done when
    You click Noted. One click, and the whole brief is handled.

Triage modeIn review

One email at a time. One key each.

Triage mode shows a single conversation and waits for a decision. Press D, H or K and the next one appears. A busy morning inbox becomes a few minutes of choices.

  • DoD
  • Hand overH
  • KnowK

Where it stands

Built in the open, shipped in pieces.

tresso is not released yet. This is what the open source code does today, what is being reviewed, and what is being built.

Available
  • Unified Inbox for IMAP, Gmail and Microsoft 365
  • Search, compose, drafts and signatures
  • Smart inboxes with rule-based classification
  • Todos, with Make todo from any email
  • Calendar with CalDAV, recurrence and invitations
  • Reminders on every device
  • Attachment virus scanning with quarantine
  • Desktop app with a local copy of your mail
  • Mobile app, including compose with files
In review
  • Hand over with Waiting on and nudges
  • Triage mode with D, H and K
  • Daily brief with one-click Noted
  • Batched delivery and one-click unsubscribe
  • Push for mail that needs you
  • Bulk cleanup by sender, smart inbox or age
  • Calendar views, event editor and finding a time
In progress
  • Per-user encryption of stored mail at rest
  • Google and Microsoft calendars

Follow along on GitHub

Inside

Everything an email client should do, and a clear next step for every message.

  • Unified Inbox

    IMAP accounts, Gmail and Microsoft 365 in one inbox, sorted into smart inboxes: To do, Informational, Notifications, Newsletters, Invitations and Spam.

  • Built-in todos

    Turn any email into a todo, or let a smart inbox do it for you. Todos live next to your mail and sync across devices.

  • Calendar included

    Your CalDAV calendars with recurring events, invitations you answer from the email, and reminders on every device.

  • Search everything

    Find any message across all your accounts.

  • Virus scanning

    Attachments are scanned before anything can be opened. Infected files go to quarantine.

  • Every device

    Web, desktop and mobile apps. The desktop app keeps a local copy of your mail, and the phone can write mail with files.

All features

Two ways to run it

Host it yourself, or let us run it.

The same client either way. The open source edition is complete on its own; tresso Cloud will add what needs a service behind it.

Open source, self-hosted

tresso

A complete email client for one person. Run it on your own server with Docker.

  • All your accounts in one inbox
  • Do, hand over, know, with todos and a daily brief
  • Smart inboxes with your own rules
  • Calendar with CalDAV and reminders
  • Web, desktop and mobile apps
  • AGPL-3.0, free forever
Self-host tresso

Hosted by us, planned

tresso Cloud

Everything in the open source edition, run for you, plus the parts that need a service. Designed, not built yet.

  • AI classification that learns from you
  • AI todo extraction and summaries in your brief
  • Teams with shared inboxes and delegation
  • REST API, webhooks and an MCP endpoint
  • Statistics and your yearly Year in mail
See Cloud plans

An inbox that empties on purpose.

tresso is in active development. Downloads for web, desktop and mobile arrive with the first release.

Get the apps