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Convert MSO to XLS

Can you convert MSO to XLS?
Verified by Adam B.· reviewed by FE Editorial ·updated Aug 17, 2026
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Is it possible to convert MSO to XLS?
No - not a direct conversion.

The oledata.mso file holds rendering plumbing for embedded OLE objects in an email, not a workbook. Ask the sender to resend the .xls or .xlsx file as a normal attachment and to switch their Outlook format to HTML or Plain Text.

No direct path
Also to XLS: WDB · ACCDR · XLR

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Tested on macOS, Windows & Linux
Last verified Oct 2026

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Why convert MSO to XLS?

Outlook generates oledata.mso automatically when a message is composed in Rich Text or Word format and contains embedded OLE objects. Even if an Excel chart was embedded in the email body, only partial display data ends up in oledata.mso - not a complete workbook. A .xls file is a full OLE2 BIFF8 workbook with cell records, formulas, and sheets; none of that structure is present in .mso.

How to convert MSO to XLS

Microsoft Excel APP

Ask the sender to drag the .xls or .xlsx file directly into the email as a normal attachment; once received, open it in Microsoft Excel.

7-Zip FREE

Advanced users can decompress the ActiveMime payload and inspect the inner OLE structure in 7-Zip, but the embedded object data is partial display information - a complete .xls workbook cannot be recovered this way.

Programs that convert MSO

Microsoft Excel

About these formats

.MSO Microsoft Office HTML/OLE Data Stream (oledata.mso)

An MSO file - most often named oledata.mso or editdata.mso - is not a document. It is a formatting attachment Outlook adds automatically when a sender composes HTML/Word-format e-mail…

Open .MSO details →
.XLS Microsoft Excel 97-2003 Workbook (Binary Interchange File Format, BIFF8)

An XLS file is an old-format Microsoft Excel spreadsheet from the Excel 97-2003 era, saved as a binary file rather than the ZIP-based XLSX used since 2007. You can open it free without…

Open .XLS details →

Quality & what to watch

  • Online converters claiming to convert .mso to .xls produce garbage output - the source data is not a spreadsheet.
  • Renaming oledata.mso to .xls does not change its internal structure; Microsoft Excel will reject it.
  • The sender should change their Outlook message format to HTML or Plain Text (File > Options > Mail) to prevent .mso from being generated.

Frequently asked questions

Is there any tool that can extract a spreadsheet from oledata.mso?
No reliable one - the embedded object data inside .mso is partial display information, not a complete workbook, so no usable .xls file can be recovered.
Why does the file have a .mso extension instead of .xls?
The extension reflects what Outlook generated, not what the sender intended to share; renaming it to .xls does not make Excel open it.
Is oledata.mso the same as winmail.dat?
winmail.dat is a TNEF container that can hide real attachments inside it; oledata.mso is an ActiveMime wrapper for OLE object data and does not contain the spreadsheet you were expecting.