How to open a .msg file on a Mac
Short answer
Install OldMail from the Mac App Store and double-click the .msg file, or press ⌘O and select it. The message opens with its formatting, inline images and attachments intact. You can set OldMail as the default app for .msg so double-clicking always works.
If you only need the text and can wait, the simplest zero-install option is to ask the sender to forward the message normally instead of attaching it — details below.
What is a .msg file?
A .msg file is a single email message saved by Microsoft Outlook on Windows. You usually receive one because someone dragged an email out of Outlook onto their desktop and attached it, or forwarded a message "as attachment".
Inside, it is not plain text. Outlook saves it in a Microsoft container format (the same structured-storage layout old Office documents used), with the subject, sender, recipients, body and every attachment stored as separate streams. That is why opening one in TextEdit shows a screenful of binary noise with a few readable words scattered through it.
Why renaming it to .eml does not work
It is the first thing everyone tries, and it is worth explaining why it fails. An .eml file is plain RFC 822 text — headers at the top, body underneath. A .msg is a binary container with a completely different internal structure.
Changing the extension only changes the label. The bytes are still in Outlook's format, so the app you hand it to still cannot read it — you have just made the error message more confusing.
Genuine conversion means parsing the container and rebuilding the message, which is what a tool that understands the format does for you.
Open a .msg file on your Mac in three steps
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Install OldMail
Free on the Mac App Store, macOS 13 or later.
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Open the message
Double-click the file, drag it onto the window, or press ⌘O and select it. It opens in its own tab with the sender, recipients, date and full formatted body.
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Make it the default (optional)
In OldMail's settings you can register it as the default app for
.msg— and for.eml,.emlx,.ostand.pst— so double-clicking any of them just works from then on.
Everything happens on your Mac: no account, no sign-in, and no copy of your mailbox sent to a server.
Other ways to do it
OldMail is not the only route, and depending on what you have available another one may suit you better.
Ask the sender to forward it normally
If they forward the message rather than attaching it, you get an ordinary email you can read anywhere. Free, instant, and often the right answer — though it does not help with a folder of a hundred archived .msg files.
Ask for it as .eml instead
Most mail clients, including Outlook, can save a message as .eml. Apple Mail opens those natively.
Online .msg viewers
They work, but you would be uploading the message and its attachments to someone else's server to read it. For anything confidential that is a poor trade for saving a small download.
Common problems
The date shows as today
Some viewers fall back to the file's timestamp because the real date is stored as an Outlook property rather than a normal header. OldMail reads the sent and delivery properties, so the original date is shown.
The sender looks like /O=EXCHANGE/CN=…
That is an internal Exchange address rather than an email address. Where an actual SMTP address is present in the message, it is used instead, so you see a name and a normal address.
I have a whole folder of them
Point OldMail at the folder rather than at one file and every message inside opens in a single tab with a searchable list — no need to open them one at a time.
Open it in about a minute
OldMail is free on the Mac App Store. It reads MSG files — and PST, OST, EML, EMLX and MBOX — without Outlook and without uploading anything.
Frequently asked questions
How do I open a .msg file on a Mac?
Install OldMail from the Mac App Store and double-click the file, or press ⌘O and select it. The message opens with its formatting, inline images and attachments. You can also set OldMail as the default app for .msg files.
Can I just rename the .msg file to .eml?
No. A .msg is a binary Outlook container and an .eml is plain RFC 822 text, so renaming only changes the label while the contents stay unreadable. The file has to be parsed and rebuilt, which is what a viewer that understands the format does.
Can Apple Mail open .msg files?
Apple Mail handles .eml files but not Outlook's .msg format. Either ask the sender to supply an .eml, or use an app that reads .msg directly.
Will attachments inside the .msg still work?
Yes. Attachments are listed with file-type icons and can be opened or saved anywhere you like.
Can I convert a .msg to PDF on a Mac?
Yes. With the message open, press ⇧⌘E to export it as a PDF or a Word document, complete with subject, sender, recipients and date. Attachment names and types are listed under the subject without being embedded, so the document stays small.