Convert an Outlook OST file into individual .eml messages, each saved with full headers, body formatting, and attachments. The converter packages all resulting .eml files into a single ZIP that mirrors the original folder hierarchy, so you keep your mail organized after extraction. Works for standard Unicode OST files; very old non‑Unicode OSTs are outside the tool’s scope.

Full header preservation

Every standard email header—From, To, Cc, Subject, Date, and Message‑Id—is written into each .eml exactly as it appears in the original OST, allowing downstream mail clients to recognise the original sender and routing information.

Body and attachment fidelity

HTML bodies retain their formatting while plain‑text bodies stay unchanged, and all file attachments are included as MIME parts within the .eml. Inline images keep their content‑id references so they display correctly without extra processing.

Original folder hierarchy retained

The converter recreates the Outlook folder tree inside the output ZIP archive, placing each .eml in the corresponding sub‑folder so the organization of messages mirrors the source OST.

Supported OST scope

The tool processes standard Unicode Outlook OST files, covering the vast majority of modern Outlook installations. Very old non‑Unicode OST files are outside the tool’s scope; users with such archives would need a legacy‑format solution before migration.

Limits and scope

Output format: All extracted messages are packaged into a single ZIP archive; individual .eml files are not offered as separate downloads.
File size and retention: Upload limits vary by account tier, and the generated download link remains active for 24 hours after conversion.

How to convert OST to EML

STEP 1

Upload your file

Click inside the file drop area to upload your files or drag & drop them.

STEP 2

Convert

Click on the "Convert" button. Your files will be uploaded and converted immediately.

STEP 3

Download

Download link of converted EML files will be available instantly after conversion.

STEP 4

Feedback

Check conversion results and send us your feedback.

FAQ

Are all original email headers retained in each exported .eml file?

Yes, headers such as From, To, Cc, Subject, Date, and Message‑Id are written into every .eml exactly as they appear in the source OST.

Do attachments and inline images stay attached and display correctly in the .eml files?

All file attachments are included as MIME parts inside the .eml, and inline images keep their content‑id references so they appear inline without extra processing.

Is the Outlook folder hierarchy reproduced in the output ZIP archive?

The converter recreates the original OST folder tree inside the ZIP, placing each .eml in the corresponding sub‑folder to preserve the source organization.

What are the file‑size and batch limits for this converter?

The maximum upload size and the number of files that can be processed in a single batch depend on your account tier; signing in increases these limits compared with the anonymous allowance.

How long is the converted file available for download?

The download link for the generated ZIP archive remains active for 24 hours after conversion, after which it expires.

OST to EML

Each email is saved as an .eml file with full headers and attachments, preserving the original folder hierarchy inside a ZIP archive.