Local-first email, calendar & notes
mailSCW puts Microsoft 365, Gmail and any IMAP account in one window, with the calendars, contacts and notes that go with them. Everything it knows sits in a single database on your own machine. There is no mailSCW account, no copy of your mailbox in our infrastructure, and nothing to pay every month to read your own email.
Windows · macOS · Linux · one codebase, one database format
The trade nobody mentions
Pick anything on the market and you are handing over privacy, platforms or capability. Usually two of the three.
Heavy, Microsoft-first, and genuinely good only when your whole working life already lives on Exchange.
Fast, and still a browser tab. No real offline, no local search, one ecosystem, and the mailbox is the product.
Polished. Your mail is relayed through and stored on their servers, and you rent access to it for as long as you want to keep reading it.
Private, free, and working roughly the way it did a decade ago. The calendar is an add-on with opinions of its own.
Excellent, and the closest thing to this in spirit. macOS only, Gmail only. That rules out most people before they start.
Nothing is private, current, multi-provider and on all three desktops at the same time. mailSCW is the attempt at all four at once.
Privacy first
Most clients tell you what they promise to do with your mail. mailSCW is built so that the promise is mostly unnecessary: there is no server of ours for your mail to sit on, so there is nothing for us to undertake not to read, sell, index or lose.
Microsoft Graph, Gmail, IMAP, CalDAV — your own accounts, contacted directly by the app on your machine.
One small server we run, forwarding a notice of roughly 200 bytes that says "account X changed". No subjects, no bodies, no attachments.
Only when you press an AI button, only on a key you supply, and only the text that action needed.
No mailbox mirror. No content telemetry. No third-party sync service between your own two computers.
In the reader
Tracking pixels are detected when the body is fetched and flagged per message, so you can see which senders are watching you open their mail. Remote images stay off until you allow them, then cache locally with a lifetime you set — a sender does not get a fresh ping every time you reopen a thread.
Outbound
One-click unsubscribe takes its target from a header the sender wrote, and the request leaves from inside your network. mailSCW follows those redirects itself and checks every hop: still HTTPS, never a private, loopback or link-local address. Chromium would happily walk that chain for you. It does not get to.
On disk
Saved attachments are written with the internet zone marker, so Word and Excel open them in Protected View instead of trusting them because they came off your own drive. Your API keys never cross into the UI layer at all — they are read and used in the main process only.
The full privacy and security detail, mechanism by mechanism →
What it is
Not a Gmail client with IMAP bolted on the side. Each provider is implemented properly, in its own module, against its own API — so shared mailboxes, labels, categories and delta sync all behave the way that provider expects.
Calendar
Contacts
And the rest
All of it in one window, all of it offline. Mail, calendar, contacts and notes share one local database, so a search hits everything at once and nothing waits on a network round trip.
The product
Sender, subject and a preview line when you are reading. Three times the rows when you are triaging. Same folder, same app, one setting.
The one nobody else has
Two jobs, two calendars, one human being. mailSCW keeps your busy time in step between them, in any direction, without inviting anybody to anything.
The hard parts
AI
No AI subscription, no shared endpoint, no mailbox handed to a vendor as training data. You bring a key from a provider you already trust, mailSCW uses it, and it shows you what each call cost.
In your mail
In your notes
How it behaves
Finding things
Not a search that returns messages you then have to open. The attachments view is one row per file, with its own name, type and size — a message with four attachments is four rows. Inline images are left out, so what you see is the files people actually sent you.
Every term matches the file name, the sender or the subject. Add as many as you like and flip any of them to exclude. "Invoice, not draft" is two clicks.
Or pick one and narrow to a folder using the same tree the mail view uses. Click a row to open the message it arrived in.
No search round trip, no repeating yourself per account, and the list is there with the network off.
Sync
Microsoft Graph and Google push notifications land mail and calendar changes in seconds instead of waiting out a poll interval.
Gmail changes arrive over an IDLE connection and Google Cloud Pub/Sub, again with no message content passing through anything of ours.
Every push path asks whether the relay understands it and reverts to a timer if the answer never comes. A push feature is not allowed to break the app.
Both calendar providers sync from a stored cursor and both mail providers sync deltas, so a mailbox with hundreds of thousands of messages costs about the same per tick as a small one.
This is developed against a mailbox with roughly 166,000 messages in it, which is where most of the unglamorous work has gone: deleting thousands of messages, marking a huge folder read and running a rule over a year of mail all happen without locking up the window. Composer keystroke latency and reply-open time were each profiled and fixed rather than left at good enough.
Depth
Competitors have some of these. The list below is the short version — every one of them is in the shipping app, on every platform it runs on.
Calendar
The app itself
Two computers
Notes and settings sync between your machines through a hidden folder in a mailbox you already own. No mailSCW backend is involved and there is nothing extra to pay for.
The usual answer
Create an account with the vendor, upload your settings — and often your mail — to their cloud, and pay monthly for the privilege of owning two computers.
This one
A folder in your own mailbox that you can open, export or delete. Your data, in your account, the whole way through.
The short version
| mailSCW | Outlook | Gmail web | Spark / Superhuman | Thunderbird | |
|---|---|---|---|---|---|
| Mail stored locally, works offline | Yes | Partial | No | Cached | Yes |
| Mail relayed through a vendor server | Never | n/a | n/a | Yes | Never |
| Windows, macOS and Linux | Yes | Win / Mac | Browser | Win / Mac | Yes |
| Microsoft 365, Gmail and IMAP together | Yes | Partial | No | Yes | Yes |
| Calendar mirroring across accounts | Yes | No | No | No | No |
| AI on your own key, no subscription | Yes | Copilot | Gemini | Bundled | No |
| Meeting recording built in | Yes | No | No | No | No |
| Mail merge from a CSV | Yes | With Word | No | No | Add-on |
| Multi-PC sync without a vendor account | Yes | No | No | No | No |
| Cost model | Buy it once | Microsoft 365 | Free / ads | Subscription | Free |
Why this is where email is going
For fifteen years the trade was worth it. Storage was expensive, laptops were slow, and putting the mailbox on somebody else's machine bought you search, sync and a phone client you could not otherwise have had. That bargain has quietly expired. A cheap laptop has a fast SSD and enough RAM to hold a decade of mail locally, and the providers all expose delta APIs that make keeping a local copy current a solved problem rather than a research project.
What has changed underneath it is who wants your mailbox. An inbox is now the most valuable training corpus most people own, and the clients in the middle are the ones with access. A design where the mail never leaves your disk is not nostalgia — it is the only version of this that stays yours when the terms of service are rewritten.
So the bet is a simple one. Everything that made a web client feel modern — instant search, push in seconds, working across your accounts, AI that actually helps — is achievable on the desktop now, and it is achievable without a vendor holding the mailbox. mailSCW is what that looks like when you refuse the trade instead of negotiating it down.
Roadmap
Near term
Reach
The big ones
The hard part is behind it. Multi-provider sync, a local database that survives a real mailbox, push, calendar mirroring and AI are all shipping. What is left is breadth.
Wait list
mailSCW is with a small group of testers while the rough edges come off. Leave an address and you will hear when there is room for more — once, by email, and not for anything else.
All three update themselves from inside the app, and share one database format.
mailSCW