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.msg

Outlook Message

Email & Calendar

MSG is Outlook’s message format and may store a body, attachments and properties. New Outlook’s MSG support has subscription requirements; the Outlook name alone does not establish availability.

What it is used for
Individual Outlook messages and related items
What the file contains
Binary data
All sections, questions and sources

Content reviewed： · Editor：Kai

First: choose for your purpose

MSG is an Outlook message file. Identify whether you use classic, new or web Outlook. MSG opening in new/web Outlook requires a qualifying Microsoft 365 subscription. Renaming to EML or PDF does not convert it.

Opening steps

Choose your environment or purpose to see its steps.

Windows: classic Outlook

Distinguish saved messages from your current inbox.

  1. Copy the MSG locally and launch classic Outlook.
  2. Double-click the MSG or choose Outlook through Open with.
  3. Inspect subject, body, date and attachments. Check recipients and message status before reusing it.
New / web Outlook: check eligibility

Separate account eligibility from file corruption.

  1. Open Outlook with an account that has a qualifying Microsoft 365 subscription.
  2. Drag the MSG from the computer to the reading pane. For the web version, check whether cloud use is permitted for this message.
  3. If opening fails, check the subscription and version, then use a supported desktop client or request EML/PDF from the sender.
Mac / mobile: request a suitable format

For reading, you can request a usable copy.

  1. Check the exact application’s MSG support; do not assume it matches Windows.
  2. If unsupported, ask the source Outlook user for a body PDF and separate required attachments.
  3. Keep the MSG for records and compare the supplied PDF and attachments with the message.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

  • New Outlook cannot open it: check version, subscription and support conditions.
  • Attachment fails: message support does not establish attachment-format support.
  • Different display elsewhere: inspect Outlook version, fonts, body format and external resources.
  • Only MSG fails in new Outlook: EML support and MSG subscription requirements differ. Check account eligibility.
  • Web opening is restricted: check organizational data rules and browser restrictions, and use an approved desktop route.
  • An attachment is listed but will not open: MSG support does not imply support for its attachment type. Save it separately and inspect with the appropriate application.

MSG → PDF / another mail format

  1. Open in supported Outlook and print to PDF; inspect subject, recipients and body.
  2. If EML is required, use a supported export/migration workflow and compare attachments afterward.
  3. After conversion, inspect attachment counts/sizes and recipient display; retain the MSG.

Renaming MSG to EML does not convert it. Retain the original and required attachments.

Outlook editions and MSG support

Outlook editions differ across classic Windows, new Windows, web, Mac and mobile. The linked Microsoft procedure covers new/web Outlook. Include edition and subscription information when asking for help.

Source for these steps：Microsoft · Open .eml, .msg, and .oft files in new Outlook

What a body PDF cannot preserve

A printed PDF may omit attachments, custom fields or complete headers. Keep a reading PDF separately from the MSG record and avoid overwriting identically named attachments.

Opening an MSG does not establish that its reply destination is trustworthy. Verify payment or sign-in requests through your usual independent channel.

Source for these steps：IETF / RFC Editor · RFC 5322 — Internet Message Format

Related-format differences

Related-format differences
Format / choicePurpose and preserved information
MSGOutlook message record; check edition and account requirements.
EMLMessage format used by multiple mail clients, subject to application support.
PDFReadable body copy; retain attachments and original separately.

Handling and security

Verify origin before opening links/attachments; review recipient information, quoted history and private attachment content before sharing.

Questions and answers

Can every Outlook installation open MSG?

Check version, subscription and item support.

Can I rename MSG to EML?

That does not convert its internal format.

Can PDF replace the original?

It may omit attachments/properties; keep the MSG.

Does free new Outlook always open MSG?

No. Microsoft specifies a qualifying Microsoft 365 subscription for MSG/OFT opening. EML has different conditions.

Can I rename MSG to EML before sending it?

Their structures differ, so renaming is not conversion. Use a supported Outlook export or provide a body PDF and separate attachments.

Format facts: name, steward and MIME type
Formal name
Outlook message file
Steward / specification
Microsoft
MIME type
Depends on the producer or server; an extension alone does not establish a MIME type.

Primary and official sources