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Univik Online MBOX Viewer
100% private. Runs only on your device
Read the Local Folders and ImapMail mailboxes from a PostboxApp profile with no Postbox and no licence, on a Mac, a PC or a phone. Nothing installed, nothing sent out.
Or pick it from your device. Messages open in this tab, on your own computer, phone or tablet. Your mailbox is never uploaded.
Postbox is a paid client, and when the licence lapses or the app is gone the mail is still sitting in the profile as plain mbox files. This page reads those files in your browser, right where they are, with nothing sent to a server.
Open Inbox or Sent as Postbox left them. The tool reads the mailbox file itself, so nothing has to be exported first.
A lapsed subscription locks the app, not your data. The files open here on any machine, whether or not Postbox was ever installed on it.
Postbox ships for Mac and Windows only. Its mail files, though, read the same on Linux, a Chromebook or a phone through this page.
Save a message as .eml, or download one attachment or every attachment as a zip. The current list can go out as .csv.
Short answer: copy Inbox out of the PostboxApp profile to any device and open this page there. The device does not need Postbox, a licence or any mail client.
Use Go to Folder in Finder with the Application Support path below, copy a mailbox out and open it in Safari or Chrome. The app can stay closed.
Type %APPDATA%\PostboxApp\Profiles into the File Explorer address bar, open the profile and copy a mailbox out. Load it in Edge, Chrome or Firefox.
There is no Postbox for Linux, so this is the way to read a profile copied over from a Mac or PC. Any browser on any distribution does it.
Postbox has no mobile app. Put the mailbox file in a cloud folder, pick it here in the browser on a phone or an iPad and read the archive on the go.
Move the file over on a USB stick or through Drive and pick it in Chrome. No client of any kind is involved.
Postbox grew out of Mozilla code, so its mail store follows the Thunderbird pattern with a couple of Postbox specific extras. The tool handles all of it.
Messages start with a From - line and a date. The tool splits on those, so the count you see equals the count Postbox showed.
Postbox writes temporary cache files whose names contain #PB#, plus the usual .msf summary files. Pick a folder and the tool leaves both kinds alone and opens only real mailboxes.
X-Mozilla-Status and X-Mozilla-Status2 lines are preserved in the Headers tab beside Message-ID and Received, exactly as the profile stores them.
POP and local mailboxes live under Local Folders. ImapMail holds a separate folder per IMAP account with an offline copy of whatever was synced. Both open the same way.
Every attachment is listed on its own tab. HTML mail keeps inline pictures, and remote images stay off until you ask for them.
A profile from a Mac uses LF, one from Windows uses CRLF. The tool reads either, so a mailbox moved between the two keeps every message.
On a Mac go to Library, Application Support, PostboxApp, Profiles. On Windows go to AppData, Roaming, PostboxApp, Profiles. Open your profile and its Mail folder. Local Folders holds local mail and ImapMail holds each account.
Copy Inbox or Sent out of that folder and drag it into the upload area on this page. Skip the .msf and #PB# files.
Open a message and flip between the Plain text view, the Headers tab and the Attachments tab. Save anything you want as .eml or as a zip of attachments.
Postbox Inc. documents the default locations. If you moved an account with the Local Storage setting, look in the folder you chose instead.
~/Library/Application Support/PostboxApp/Profiles/[your.profile]/Mail/Local Folders for POP and local mail, and .../ImapMail for IMAP accounts. Library is hidden, so use Go to Folder.
C:\Users\[you]\AppData\Roaming\PostboxApp\Profiles\[your.profile]\Mail\Local Folders and \ImapMail. If there is no PostboxApp folder, look for one named Postbox from an older release.
An IMAP folder only holds what Postbox downloaded. Before copying it, right click the folder in Postbox and open Properties. On the Synchronization tab click Download Now so the offline copy is complete.
Account Settings, then Local Storage, lets each account point at a Local directory of your choosing. If that was set, the mailboxes are there rather than in the profile. Postbox Inc. suggests switching to offline mode before moving them.
Postbox will not import a single .mbox file. Put the file inside a parent folder, then use File, Import and choose that folder. It lands under an Imported Mail account.
Read one Postbox mailbox anywhere with this online page. When the job is a whole profile with every account and subfolder, plus search inside message text and printing, the free Univik MBOX Viewer for Windows is the better fit.
| Feature | Online Postbox Viewer | MBOX Viewer for Windows |
|---|---|---|
| Install needed | None, opens in the browser | 15 MB Windows setup |
| Operating system | Windows, Mac, Linux, Chromebook, iOS, Android | Windows 7 to 11 |
| Files uploaded | Never, runs on your device | Never, runs on your PC |
| Postbox profile | One folder at a time | Every account and subfolder |
| Search | Sender, subject, recipients | Message bodies too |
| Large mailboxes | Read in pieces, multi GB files open | No size limit |
| Browser print of the open message | Direct printing | |
| Price | Free | Free |
Yes. The licence controls the application, not the mailbox files in the profile. Copy Inbox or any other mailbox out of the PostboxApp profile folder and open it on this page. Everything you had is readable, attachments included.
The ones with a plain folder name and no extension: Inbox, Sent, Drafts, Trash and any folder you created. Files ending in .msf are indexes and files with #PB# in the name are temporary cache. Postbox Inc. describes both as not needed, and the tool ignores them.
Near enough. Postbox was built on Mozilla code, so the mailbox layout, the From dash separator and the X-Mozilla headers match. The differences are the profile location, the PostboxApp folder name and the #PB# cache files. A mailbox from either program opens here the same way.
Because the ImapMail copy only contains what Postbox had pulled down from the server. Headers may be there while bodies are not. In Postbox, right click the folder and choose Properties. On the Synchronization tab click Download Now, then copy the file again.
Under your home folder in Library, Application Support, PostboxApp, Profiles, then your profile and its Mail folder. Local Folders holds POP and local mailboxes, ImapMail holds each IMAP account. Finder hides Library, so press Command Shift G and paste the path.
No. Your browser pulls the mailbox off your own disk and assembles the list by itself. No server takes part and no sign in exists. Switch the network off once the page is up and it still reads your mail.
Yes. Click Select a folder and pick Local Folders. Every mailbox in it loads and a selector at the top of the page switches between them. The .msf and #PB# files are filtered out automatically, so only real mailboxes appear in the list.
Open the mailbox here, pick the messages you want and save each as .eml. An .eml file drags straight into Outlook, Apple Mail or Thunderbird with its headers and attachments intact. For a whole profile at once, use the Windows viewer linked above.
Take Inbox out of the PostboxApp profile and read it here, licence or no licence. The file never leaves your computer.
Choose a Postbox mail file