How to open a .OST file online
No mail account and no extra software to install.
Pick your .OST file
Drag it in or click to choose it. It opens here in a moment.
Read it safely
The message opens in a locked-down view: scripts never run, and remote images often used for tracking stay blocked until you allow them.
Check and save
Download attachments, read the full headers, and see every server the message passed through, with SPF, DKIM and DMARC results.
About .OST files
What a .OST file is, and what's inside it.
An OST file is an Outlook Offline Folder File developed by Microsoft. It contains data used for offline access to email and other information, which synchronizes with a server when a connection is available. These files are typically opened with Microsoft Outlook or managed using specialized recovery and conversion utilities.
Programs that open .OST files
| Full name | Outlook Offline Storage Table |
|---|---|
| Developer | Microsoft |
| First released | 1997 (Outlook 97); modern Unicode OST since Outlook 2003 |
| Category | |
| MIME type | application/vnd.ms-outlook |
| Signature | 21 42 44 4E "!BDN" - Outlook PST/OST file signature |
Related viewers
Open the attachments you find.
Is it safe to open a suspicious .OST file here?
Safer than in a mail client: the message runs in an isolated frame with scripts disabled, remote images and trackers are blocked until you allow them, and attachments are never opened automatically.
How can I tell if an e-mail is fake?
Look at the Message info panel. We show the SPF, DKIM and DMARC results recorded by the receiving server, warn you when the Reply-To address differs from the sender, and list every server the message passed through.
Can I open a Gmail or Thunderbird mailbox (.mbox)?
Yes. Drop the .mbox file and you'll get a searchable list of every message. Click one to read it.
Why does my MSG file show plain text only?
Some Outlook messages store their formatting only as compressed RTF. We show the text today; full RTF formatting is coming soon.
Can I open .pst or .ost files?
Not yet. Outlook data files are on our roadmap. Meanwhile you can export single messages from Outlook as .msg and open them here.
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