Convert OST files to MSG format online. Free tool, EU servers, GDPR compliant, auto-delete 24h. No software to install.
| Feature | OST | MSG |
|---|---|---|
| Ecosystem | Microsoft Exchange / Outlook | Microsoft Outlook |
| File structure | Binary database (similar to PST) | OLE2 compound document |
| Openness | Proprietary Microsoft format | Proprietary Microsoft format |
| Platform | Windows (requires Exchange profile) | Windows (Outlook preferred) |
| Data types | Email + calendar + contacts + tasks | Single email with rich metadata |
| Free readers | None without Outlook/Exchange | Limited |
Import the OST file into a compatible email client, then export in MSG format. This requires having both source and target applications installed.
Pros
Cons
Several desktop converters can handle the OST to MSG conversion locally. These paid tools typically cost between $29 and $99 per license.
Pros
Cons
Upload your OST file to MailtoPst, select MSG as the output, and download. Works from any browser, no software needed.
Pros
Cons
Step by step
Drag & drop or click to upload your .ost file. Files up to 51 GB supported with resumable upload.
Select MSG from the format dropdown. MailtoPst auto-detects the best conversion settings.
Conversion takes seconds. Download your .msg file or receive it by email.
100 MB free credit. No credit card required.
FAQ
Yes. MailtoPst reads OST files server-side — you don't need Microsoft Outlook (Exchange cache) installed. Just upload the file from any browser on any operating system.
Yes. MailtoPst preserves the original folder hierarchy from your OST file when converting to MSG.
Your first conversion is free with no credit card required. Credit packs start from €4.99.
MailtoPst preserves all attachments, email headers, timestamps, read/unread status, and other metadata during the conversion.
MailtoPst supports files up to 50 GB with resumable upload technology. If your connection drops, you can resume where you left off.
First conversion free. No credit card required.