Encrypted on your PC
The mail cache is encrypted with AES-256. Its key is sealed to your Windows account, so the file is useless if it is copied off your PC.
Version 0.1.39 for Windows
Outlook's way of working. None of the watching.
Obsidian Mail Client puts Mail, Calendar, People and To Do in one window, with the ribbon and keyboard shortcuts you already know. It blocks tracking pixels, encrypts the mail it keeps on your PC and filters spam with a filter that learns from you. Your mail stays between your PC and your mail provider.
- Windows 10 & 11
- Outlook.com · Microsoft 365 · Exchange · Gmail · IMAP
- Encrypted on disk
- Signed updates
Works with
Outlook.com & Hotmail
Microsoft 365
Exchange Server
Obsidian Mail Server
Gmail
Any IMAP server (Fastmail, iCloud, your own)
01One window
Mail, calendar, contacts and tasks together
The rail on the left switches between the four, as in Outlook. With a Microsoft account they sync with Outlook.com; contacts and tasks also work on their own, kept on your PC.
Ctrl+1Mail
Several accounts in one folder pane with All Inboxes, favorites, conversations, and a reading pane on the right, at the bottom or off.
Ctrl+2Calendar
Day, work week, week and month. Recurring events, reminders, conflicts shown as you pick a time, and invitations answered from the message.
Ctrl+3People
Contacts and groups, contact cards, and addresses completed as you type from everyone you write to.
Ctrl+4To Do
Tasks with steps, due dates, reminders and lists. Flag a message and it shows up as a task.
Nothing new to learn
If you have used Outlook, you already know where everything is. The ribbon has the same tabs, the shortcuts are the same, and right-clicking a message or a folder offers what you expect.
- The Office ribbon. File, Home, Send / Receive, Folder, View and Help. In a narrow window the groups fold into drop-downs; Alt shows key tips and Ctrl + F1 hides it.
- Outlook's shortcuts. Ctrl + R to reply, Ctrl + Q to mark read, Insert to flag, F9 to sync, Ctrl + E to search.
- Drag and drop messages onto folders, open a message in its own window, or print it with its header.
- Eleven colour themes. Obsidian, Midnight, Forest, Ember, Crimson and Graphite in the dark; Ocean, Lavender, Rose, Sand and Sage in the light.
- Options as in Outlook. Options, Rules and every dialog open in a window of their own over the app, with the sections on the left and OK and Cancel at the bottom.
- Color categories. Outlook's 25 colors and its Ctrl + F2–F12 keys, shared with Outlook on the web and with your Obsidian Mail Server.
- Automatic replies. Out of office from File > Info, kept by Outlook.com, Microsoft 365, Exchange or your Obsidian Mail Server so they go out with your PC off.
- Search like Outlook. Type
from:,subject:,has:attachmentorreceived:this week, or let the Filters button write them for you. - Pictures and tables in the messages you write, and drafts that open again right where you left them.
- Your Obsidian Mail Server account. Mail, calendar, contacts and tasks from your organization's own server over Exchange ActiveSync, with new mail the moment it arrives.
- Bring your old mail. Import an Outlook
.pstor.ost, an.mboxor.emlfiles straight into an account. - Take it with you. Export a folder to
.mbox, a calendar to.icsand contacts to.vcf, or everything into an Obsidian Data File: our own.pst, encrypted with a password if you like, that opens in its own window.
02Privacy
Your mail is not the product
There are no ads and no AI reading your messages. The app keeps a copy of your mail so it opens instantly and works offline, and that copy is encrypted. Senders who try to find out when you open their mail find out nothing.
Locked with Windows Hello
Turn on the app lock and the app asks for your face, fingerprint or PIN when it starts, and again whenever it comes back from the tray.
Tracking pixels blocked
Pictures stay off until you ask for them, and the invisible pixels that report when you read a message stay blocked even then.
Links without tags
Links open without the tracking tags that newsletters add to see who clicked what.
Who really sent it
Every message shows whether it passed SPF, DKIM and DMARC. Verified brands show their real logo, so a fake one stands out.
Signed and encrypted mail
S/MIME as in Outlook: sign or encrypt any message with a certificate from Windows' own store. Encrypted mail is never saved decrypted.
03Spam & phishing
A spam filter that learns from you
Every new message is scored on your PC by content rules and a filter that learns from what you mark. Spam goes to a Quarantine folder on your account, so you can look it over and release anything that belongs in your Inbox.
- It learns. Mark a message as spam, or release one that wasn't, and the filter adjusts for next time.
- Phishing warnings above messages with deceptive links.
- Allow and block lists. Everyone you write to is trusted automatically.
- One-click unsubscribe, then Sweep clears out everything that sender already sent.
04Everyday mail
Less time in your inbox
The tools that make Outlook.com and Outlook fast to work with, in one app.
Sweep
Clear out one sender: everything now, everything from now on, all but the latest, or anything older than a few days.
Snooze
Send a message away until later today, tomorrow, the weekend or a time you choose. It comes back unread, on top.
Undo Send & Send later
A few seconds to take a message back, or schedule it for the morning. Drafts save themselves as you type.
Quick Steps
Several actions in one click, such as reply and delete, or mark read and move. Each one gets its own shortcut.
Templates & signatures
Several signatures per account, one for new mail and another for replies, plus templates for what you write often.
Forgotten attachment
Wrote "attached" and attached nothing? You're asked before it goes. Only your own words count, not the quoted mail.
Search Folders
Unread, flagged and mail with attachments across every account, plus any search you save.
Rules
Sort mail as it arrives, or run a rule on what's already there. Create one straight from a message.
Backup & restore
Settings, lists and optionally your mail in one password-protected file, to move to a new PC.
05Part of Windows
A native Windows app
Built for Windows with WinUI 3 and .NET, not a web page in a frame. It starts quickly, stays in the tray and works with the rest of Windows.
Your mail app
Set it in Default apps: mailto: links start a message and .eml files open in their own window.
Notifications
New mail alerts with Reply, Mark as read and Delete right in the notification.
Taskbar
The unread count on the taskbar button, and a jump list for a new email or a new event.
Signed updates
The app checks for updates, verifies their signature and asks before installing: now, later, or skip.
06Only here
Things other mail apps don't do
Features you won't find in Outlook. Already installed? The app offers you the update itself.
Sender Screener
The first message from someone new waits in a Screener folder. Let them in once, or screen them out for good. People you know are never screened.
Impersonation warnings
A warning when a known name writes from an address it has never used, or when a domain only looks like one you trust.
Remind me if no reply
Pick a day as you send. If nobody has answered by then, you get a reminder and the message waits in Search Folders > Waiting for Reply.
Privacy Report
Which senders try to track you, with which tracking services, and how often the app stopped them.
Package tracking
Tracking numbers in shipping mail turn into a card that links to the carrier. Check digits are verified, so order numbers aren't mistaken for them.
Subscriptions & Bills
Receipts and bills from your mail, gathered into a list of what you pay, how often, and roughly what it adds up to each month.
Your Accounts
The services you have accounts with, found in verified mail, and which of them have had a data breach. Your address is never sent to check.
Preview safely
Look inside a Word, Excel or PowerPoint attachment without opening it. A locked-down helper reads it and no macro or link can run.
Your Addresses
A different address for every site you sign up to, using plus addressing. See who shared yours, and switch off one that gets spam.
Themes & density
Light, dark, or follow Windows, with messages darkened to match. The lists come in Roomy, Cozy and Compact.
Secure link
Encrypted mail to anyone: the message stays sealed on the Obsidian portal and the recipient gets a link to read and reply. Needs an Obsidian Suite account; how it works.
07Download
Get Obsidian Mail Client
Version 0.1.39. Installed once, it keeps itself up to date.
Downloads ask for a user name and password. Ask us for access.
For your PC
Installer
Installs for you alone, without administrator rights. The right choice for most people.
Download the installer
For IT
MSI package
Installs for every user on the PC. Needs administrator rights; deploy it with Intune, Group Policy or your own tools.
Download the MSIWindows 10 (version 1809 or later) or Windows 11, 64-bit.
08Questions
Frequently asked
Which email accounts work?
Outlook.com, Hotmail and Live accounts and Microsoft 365 work or school accounts sign in with Microsoft. Your company’s Exchange Server and your Obsidian Mail Server connect over Exchange ActiveSync. Gmail works with an app password, and any other provider works over IMAP. Type your address and the app works out which it is, as Outlook does. You can add several accounts and see them side by side.
Does anyone else read my mail?
No. Your mail goes between your PC and your mail provider. The spam filter runs on your PC, there is no AI reading your messages and no advertising.
Do I need Obsidian Suite to use it?
No. The client works with your existing mail on its own. Obsidian Suite is our hosted email security service for organizations; the Secure link feature is the only part that uses it.
Can I bring my mail from Outlook?
Yes. File > Open & Export imports an Outlook .pst or .ost file, an .mbox or .eml files into a folder of one of your accounts, keeping dates and read state.
How do updates work?
The app checks for a new version when it starts and at an interval you choose. It verifies the update's signature before it offers it, and asks whether to install now, later, or skip that version.
Windows warned me when I ran the installer. Is that normal?
For now, yes. The installer's code-signing certificate is being issued, and until it is, Microsoft Defender SmartScreen may say it doesn't recognize the app. Choose More info, then Run anyway. Updates installed by the app itself are always signature-checked.
Is there a Mac or Linux version?
No. Obsidian Mail Client is built for Windows only.
Protecting a whole organization?
Obsidian Suite filters mail for Microsoft 365, Google Workspace and Exchange before it reaches anyone's inbox, with the same filter and an AI model that explains every decision.