PostfachYour setup on every device, without a cloud.
Postfach runs no servers, so there is nothing for it to sync through. What you set up on one device, the accounts, the settings, your templates, your junk rules, reaches the next one in a file you export or in a message you send to yourself. You choose when, and you see what will change before it does.
Your mail is already the same everywhere.
Mail lives on your mail server, and every device reads it from there: the messages, the folders, what is read and what is flagged. That part needs no help from anyone.
What is each device's own is everything you set up in Postfach itself. Other apps keep that in a cloud of theirs. Postfach has none, so it gives you three ways to carry it across yourself.
- From your mail server, on every device: messages, folders, read and flagged
- Each device's own: accounts, settings, templates, folder alerts, junk rules, trusted senders
- No account with us to sign in to on a new device, because there is none
Three ways across.
Each carries something different, and each shows a summary before it changes anything.
| What travels | How | On the other device | The way back |
|---|---|---|---|
| The whole setupAccounts, settings, templates, folder alerts, junk rules | A file you export, and open there | Added to what is there. Its own accounts, templates, and rules stay as they are | It only adds, so there is little to undo. The templates as they were are kept in Template History all the same |
| TemplatesEvery folder and template | A message from one of your accounts to another | Replaced, all of them in one step | Template History keeps the last 20 states |
| Junk rulesAnd the senders you trust, or do not | A message from one of your accounts to another | Replaced. Rules for an account the sender lacks stay | Restore Junk Rules… keeps the last ten states |
A new device: the whole setup in one file.
Settings › General has a section called Move to Another Device. Export Settings… there writes one file, such as postfach.settings.2026-09-15.json, and Import Settings… on the other device reads it. Get it there any way you like: AirDrop, a shared folder, or a message to yourself.
An import adds; it does not replace. Before anything changes, a summary lists the accounts to add, each with a tick of its own and the servers its password will go to, and the templates, folder alerts, and junk rules that are new to this device. An account the device already has is left exactly as it is.
- Accounts with their servers and signatures, the settings, every template, folder alerts, and junk rules
- No passwords: each new account waits in the sidebar, marked Password needed, and connects to nothing until you sign in
- The app's own settings, such as the appearance, take the file's values unless you switch that off in the summary
- A template that reads differently on the two devices keeps this device's text, and is named
- The addresses in Postfach Contacts only if you tick Include Postfach Contacts
- A setting an older Postfach does not know is left out and named, not refused
Templates, whenever they change.
Templates are what changes most, so they have a shorter way. In the Templates settings, Send Templates by Email… mails them from one of your accounts to one the other device has too. There the message shows a banner above it, and Import… replaces that device's templates with the ones you sent, after a summary of what will change.
- Sent through your own mail server, like any message, with a copy in Sent
- The banner shows on every device that opens the message, read or not
- A message that did not come from one of your own accounts carries a warning before anything is imported
- What an import replaces is kept: Template History holds the last 20 states, each a click from being restored
Junk rules, and the senders you trust.
The same way, with one more lock. In Settings › Junk Rules, under Other Devices, Send Junk Rules by Email… mails your junk rules, and whom Postfach Contacts trusts or does not. On the other device, the banner's Import… replaces both, after a summary of what is added, removed, and changed.
This message decides which mail goes to Junk and whose mail is trusted. So Postfach offers the import only when it came from one of your own accounts. From anyone else the banner says so, and offers nothing.
- Where your mail server did not confirm the sender, the banner and the summary warn
- Not in the message: the people you wrote to. Each device reads those from its own mail
- Rules for an account the other device does not have are left out, and its own rules for an account the sender lacks stay
- What an import replaces is kept: Restore Junk Rules… holds the last ten states
- Until you send them, two devices with different rules do not argue: each moves a message once, and then leaves it alone
What stays where it is.
Some things go into no file and no message, whatever you choose. A password is the plain case: the files are not encrypted and may travel by mail, so no secret is ever written into one. You sign in to each account once on the new device, and the sign-in is kept in that device's Keychain.
- Passwords and Microsoft sign-ins
- Certificates you chose to trust: the new device asks again, as the first one did
- Your mail, which comes from the mail server
- Your purchase, which the App Store restores
- What a device did itself: which messages a rule caught, when a folder alert last notified you, the history of your templates
What it does not do.
It does not sync. Nothing travels by itself: a template you change on the Mac is on the iPhone when you send the templates again, and not before. And a send by mail replaces what the other device has, so send from the device that has the newest.
That is the price of having no servers, and Postfach says so rather than calling it sync.
- Nothing changes on a device until you import there
- Templates and junk rules by mail replace; only the settings file adds
- The files are plain text. They hold no passwords, but they do hold addresses, server names, signatures, and your templates, so keep one as you would an address book
Good to know.
Nothing of ours in between
A file goes the way you carry it, and a message goes through your own mail server. There is no Postfach account, and no server of ours that could see either.
Read whole, then asked
A file that is too large, damaged, from a newer Postfach, or not what its name says is refused before anything changes, and Postfach says why. Then comes the summary, and only your click goes on.
Files you can read
Each one is plain JSON with its date in the name, such as postfach.templates.2026-09-13.json. Open it in any editor, keep it as a backup, or compare it with an older one.
Get Postfach.
One setup, carried where you want it, on Mac, iPhone, and iPad. From the App Store, one purchase for all three.
