What an EML file is and how to open it

An EML file holds one complete email: the body, the sender and recipients, the timestamps, the attachments, and the delivery record you never normally see. It opens as soon as you drop it into a browser-based viewer, with no renaming and no Outlook. On Windows, Outlook opens it too, and on macOS the built-in Mail app does.

Why anyone uses them

A screenshot or a pasted body cannot prove the message is genuine. An EML carries the record of which servers handled it, which is what makes it usable as an original.

• Producing an email as evidence for legal or audit purposes
• Preserving a thread when a dispute arises
• Keeping a few important messages while moving between mail accounts

Opening one, with or without Outlook

Environment	How
Windows with Outlook	Double-click the file
Windows without Outlook	It opens in Notepad as unreadable code. Use a viewer instead
macOS	The built-in Mail app handles it
Webmail only (Gmail, Outlook.com)	No obvious way to open a saved .eml from your computer
Android phone	Usually no app for .eml. A viewer in the phone browser works

The webmail case is the common one. Plenty of people and small offices use only Gmail in a browser, so nothing on the computer knows what to do with an EML. A browser-based viewer fills that gap without installing anything, and the message stays on your device.

Open an EML file

An EML contains the entire message. A tool that uploads the file sends that whole email to somebody else’s server. Worth remembering with work correspondence.

Opening an EML on an Android phone

EML files often land on a phone: an attachment inside another email, a file forwarded on WhatsApp, or a backup copied from a laptop. Android has no built-in viewer for them, and tapping the file usually ends with "no app can open this file".

Open the EML viewer in Chrome or any other phone browser, tap to choose the file from Downloads or Files, and the message opens with its sender, date and body. On a phone the list and the message are two screens, and "Back" returns to the list. Attachments can be saved one by one to the phone.

About the advice to rename it to .mht

The first answer most searches return is to rename the file to .mht. It does open: Windows treats .mht as a web document and hands it to a browser or to Word.

That trick gets you as far as reading the text. But people usually open an EML for one of two reasons (to pull an attachment out, or to confirm the original), and both are exactly what renaming blocks.

There is one more cost. Renaming changes the original file. If the message may be submitted as evidence, leave it untouched.

Getting the attachments out

Attachments inside an EML are stored as encoded text, so a text editor shows only a wall of characters. You need a viewer to save them out.

Sometimes the attachment inside the email is itself a ZIP. Save it from the viewer first, then open it with the zip tool, which lists the contents and extracts them in the browser as well.

Saving an email as PDF for proof

A common reason to open an EML at all: an office, a landlord, an HR team or a lawyer wants a copy of an email as a document they can put on file. A PDF is what most people expect to receive, and it opens on any phone.

In the EML viewer, open the message, press "Save as PDF" and pick "Save as PDF" as the destination in the print window. The PDF shows what the email looked like on screen: sender, recipients, date, subject and body. Attachments are not printed into it, so save them separately and send them alongside.

• Keep the .eml as well. The PDF drops the hidden delivery record, and that record is what shows which servers handled the message.
• Do not edit anything before saving. A PDF of a changed email is no longer a copy of what you received.
• If several emails form one thread, open them together and use "Save all as PDF" to get them in a single file.
• Whether a printout is enough is up to whoever asked for it. Ask them if they want the PDF, the .eml, or both.

Reading a whole batch at once

Sometimes it is not one message. You exported a whole mail folder, legal or accounting sent over a ZIP full of emails, or you backed up your mail as .eml files years ago. Opening them one at a time gets old fast.

Drop several .eml files on the EML viewer at once, pick a folder with the "Choose folder" button, or drop a ZIP with .eml files inside (no need to unzip it), and the viewer turns into a mailbox. The list on the left shows sender, subject, first line, date and attachment count; click one and it opens on the right. On a phone the list and the message are two screens, and "Back" takes you to the list.

One search box covers sender, subject and body. Folders inside the ZIP or the dropped folder show up as filter chips, and "Has attachments" narrows the list to mails that carry files. Sort by "Newest first" or "Oldest first". "Save all as PDF" puts every mail in the current list into one PDF through the print dialog, and "Download all attachments (ZIP)" gives you one ZIP with a folder per mail. Each mail can still be saved on its own as PDF, as text or as the original .eml. Up to 1,000 emails open at once, and Outlook .msg files are not supported.

Open a batch of EML files

Storing them

• Put the date and sender in the filename. An EML tells you nothing from its name alone.
• One file per message, so a thread becomes several files. Number them in order.
• The personal data in the message is stored with it. Mind where the files live.
• .msg is an Outlook-only format and is not the same thing. Recipients may not be able to open it.