Open a PST or OST File, Convert It to MBOX.
Need to move an Outlook PST or OST mailbox somewhere else? PST to MBOX Converter opens your Outlook data file directly — with no Outlook and no Exchange server needed — and converts your mail to MBOX, PDF, or HTML, right on your Mac, iPhone, or iPad. Pick your file, see what's inside, then export it.
100% offline · on your device · no account, nothing uploaded · handles multi-GB files
Need to move an Outlook PST or OST mailbox somewhere else? The apps you're switching to — Apple Mail, Thunderbird, and others — read MBOX, not PST or OST. PST to MBOX Converter from Rush Tools opens your Outlook data file directly on your Mac, iPhone, or iPad, with no Outlook installed and no Exchange server needed, and converts your mail to the format you actually need.
It's a straightforward opener and converter, not a mailbox you read in. Pick a .pst or .ost file and the app shows a clear breakdown of what's inside — how many folders, messages, and attachments it holds — so you can confirm it's the right mailbox before you export. Then convert it to MBOX, ready for Apple Mail, Thunderbird, and other mail apps; to a clean, printable PDF; or to a browsable HTML archive you can open in any web browser. You can keep the original folder structure or flatten it, skip duplicate messages, and split a large mailbox into parts to fit import size limits.
Everything happens on your device. Your mailbox never leaves it — no account, no sign-in, and nothing is uploaded — and it handles large, multi-gigabyte files while staying faithful to the original. Seeing what's inside is free; converting and exporting are unlocked with a weekly or annual plan.
MBOX, PDF, or HTML.
Open your Outlook data file, see what's inside, then export your mail to the format that fits where it's going — all on your device, nothing uploaded.
PST / OST → MBOX
Ready to import into Apple Mail, Thunderbird, and other mail apps.
PST / OST → PDF
A clean, printable copy of your mailbox.
PST / OST → HTML
A browsable archive you can open in any web browser.
Big mailbox? No problem
Keep or flatten the folder structure, skip duplicate messages, and split large output into parts to fit import size limits.
From PST to a file you can use.
Pick your file
Add a .pst or .ost from the Files app, a download, AirDrop, or the share sheet. It opens on your device — no Outlook or Exchange server needed — and nothing is uploaded.
See what's inside
The app shows a clear breakdown — how many folders, messages, and attachments the mailbox holds — so you can confirm it's the right one before exporting.
Choose a format & options
Convert to MBOX, PDF, or HTML. Keep or flatten the folder structure, skip duplicate messages, and split a large mailbox into parts.
Export and import yourself
The app writes the file to your device. Import the MBOX into Apple Mail, Thunderbird, or another app — or just open the PDF or HTML.
Both Outlook data files, any size.
Outlook's data file. Open and convert it without Outlook.
Outlook's offline cache, including orphaned files left behind by an old profile — same conversion, no account needed.
What you can do.
Open Without Outlook
Open any .pst or .ost file directly, with no Outlook and no Exchange server needed.
See It Before You Convert
A clear breakdown shows how many folders, messages, and attachments the mailbox holds, so you export the right file.
Convert to MBOX
Export MBOX ready to import into Apple Mail, Thunderbird, and other mail apps.
Save as PDF
Keep your mail as a clean, printable PDF copy of the mailbox.
Save as HTML
Produce a browsable HTML archive you can open in any web browser — no mail app needed.
Structure & Duplicates
Keep the original folder structure or flatten it, and skip duplicate messages on the way out.
Split Large Mailboxes
Split a big mailbox into parts so it fits the import size limits of your destination app.
On-Device, Any Size
Runs on Mac, iPhone, and iPad. Everything stays on your device — no account, no upload — and it handles multi-gigabyte files.
Everything happens on your device. Your mailbox never leaves it — no account, no sign-in, and nothing is uploaded.
Opens the .pst or .ost file directly, with no Outlook installed and no Exchange server needed — so even an orphaned file still converts.
Handles large, multi-gigabyte files — fast, reliable, and faithful to the original.
- Moving an Outlook PST or OST mailbox to Apple Mail, Thunderbird, or another app.
- Converting a PST or OST to MBOX when you don't have Outlook installed.
- Opening an .ost left behind by an old profile, with no account or server to reconnect.
- Saving or archiving an old mailbox as a clean, printable PDF or a browsable HTML copy.
- Fitting a large mailbox into another app by splitting the MBOX into parts and skipping duplicates.
Opening a file and seeing what's inside is free. Converting and exporting to MBOX, PDF, or HTML are unlocked with a weekly or annual plan — no account.
Converting PST & OST.
Do I need Outlook to use it?
No. It opens your .pst or .ost file directly, with no Outlook installed and no Exchange server needed.
Which formats can it convert to?
MBOX, PDF, and HTML. MBOX imports into Apple Mail, Thunderbird, and other mail apps; PDF is a clean printable copy; HTML is a browsable archive you can open in any web browser.
Does it convert to PST or other formats?
The outputs are MBOX, PDF, and HTML. It doesn't produce PST, and it doesn't export contacts or calendar as separate files.
Can I read my emails in the app?
It's an opener and converter, not a mail reader. It shows a breakdown of what's inside — folders, messages, and attachments — so you can confirm the file, then you convert it. There's no message-by-message reading.
Does it open OST files too?
Yes. It opens .ost as well as .pst, including orphaned .ost files left behind by an old profile, with no account needed.
How do I import the MBOX afterwards?
Apple Mail, Thunderbird, and other apps each have their own MBOX import — bring the file the app produced into yours.
Is my mailbox private?
Completely. Everything runs on your device; nothing is uploaded, and there's no account or sign-in.
Can it handle a large mailbox?
Yes — it's built for large, multi-gigabyte files, and you can split the output into parts to fit your destination's import size limits.
Can I keep my folder structure?
Yes. Keep the original folder structure or flatten it, and skip duplicate messages.
Does it work online or upload my file?
Neither. It's a 100% offline, on-device converter — your file is never uploaded to any website or server.
Does it repair a corrupt PST or OST?
No. It converts readable PST and OST files; it isn't a repair tool, and a password-protected or damaged file can't be read.
Which devices does it run on?
Mac, iPhone, and iPad.
Move your Outlook mail anywhere.
Open your PST or OST, see what's inside, and convert it to MBOX, PDF, or HTML — all on your device. Seeing what's inside is free.
PST to MBOX Converter is an independent app and is not affiliated with, endorsed by, or sponsored by any email software vendor. PST, OST, and Outlook are referenced only to indicate the file formats the app works with.