What Is an EML File? Headers, Parts and How to Open One
An EML file is one email saved as plain text, with its headers, body and attachments. Jump to your question below, or work through it in order.
What Is an EML File? One saved email, stored as plain text
Short answer
An EML file is a single email message saved as plain text. It holds the headers, the body and the attachments of one message, written to the Internet Message Format in RFC 5322.
The standard fixes no first line and no header order, so an EML file has no magic number. Any mail app that reads the standard can open an EML file, and so can Notepad.
Double-click your EML file to open it in your mail app. If nothing opens, section 6 lists free ways to open an EML file on Windows, Mac and Linux.
An EML file stores one email as text: headers first, an empty line, then the body. Attachments sit inside the same EML file as encoded text.
Picture a message you need to keep. Your client sends a contract by email, and a year later there is a dispute. You drag the message from your mail app to the desktop, and a small EML file appears. It carries the subject as its name and .eml as its ending. That file is the email.
An EML file is not a folder of messages and not a mailbox backup. It is one message, which is why an EML file is so handy. You can attach it to a support ticket, send it to your lawyer or drop it in a case folder. Sender, date and every header travel with it.
The format grew out of RFC 822, written in 1982 for early network mail. RFC 2822 replaced it in 2001. The RFC 5322 standard replaced that one in October 2008 and is the version mail apps follow now. MIME, set out in RFC 2045 and its sister documents, added the parts that let an EML file carry pictures, files and text in any language.
One point of precision: the .eml ending is a naming habit among mail apps, and no RFC defines it. The message inside the file follows the Internet standards, and the ending only tells your computer which app to try.
Many mail apps write EML files. Outlook Express, Windows Mail, Mozilla Thunderbird, Opera Mail, KMail and Apple Mail are the best-known ones. Gmail gives you an EML file too: open the message, select More, then Download message, as the Gmail download guide explains.
EML file facts at a glance
| Property | Value |
|---|---|
| File extension | .eml |
| What it holds | One email message with its headers, body and attachments |
| Format | Plain text, with lines ended by a carriage return and a line feed |
| Standard | RFC 5322 for the message, plus MIME in RFC 2045 and its sister documents |
| Media type |
message/rfc822
|
| File signature |
None fixed. Many files begin with From: (hex 46 72 6F 6D 3A 20), but others begin with Received:, Date: or another header
|
| Opens in | Outlook, Thunderbird, Apple Mail, Windows Mail and any text editor |
Wrong page? If your file ends in .emlx, read the EMLX file page. If it ends in .msg, read the MSG file page.
What Is Inside an EML File? Headers on top, an empty line, then the body
Every EML file has two zones. Headers come first. One empty line ends them, and the body fills the rest.
Open any EML file in Notepad and the layout is easy to see. The top is a stack of lines that start with a name and a colon. Mail people call them header fields. The body starts after the first empty line, and nothing else marks the switch.
From: Ana Silva <ana@example.com>
To: Ben Cole <ben@example.org>
Subject: October invoice
Date: Fri, 09 Oct 2026 09:15:00 +0000
Message-ID: <a1b2c3@example.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Hi Ben,
The invoice is due on October 30. Thanks!The first three lines hold what you see in your mail app: who sent the message, who got it and what it is about. The Date line holds time and offset from UTC. Message-ID is a unique tag that gives replies something to point back to. Every EML file follows this layout.
The header fields you will meet most
Only two header fields are required by the RFC 5322 field rules: Date and From. Everything else is optional, which is why two EML files from two apps can look quite different.
| Header | What it tells you |
|---|---|
| From | The mailbox that wrote the message. It is required. |
| Date | When the sender's software created the message, with a time zone offset. It is required. It is not the time a server received the message. |
| To and Cc | The people the message was addressed to and the people copied on it. |
| Bcc | Hidden recipients. Mail software usually drops this line from the copies people receive, so a saved copy rarely shows it. |
| Subject | The title line you see in the message list. |
| Message-ID | A unique tag in angle brackets. Replies use it to point back to the message. |
| Received | One line added by every server that handled the message. The newest line sits at the top. |
| Return-Path | Where bounce notices go if the message cannot be delivered. |
| MIME-Version | Usually 1.0. It tells the reader that MIME parts may follow. |
| Content-Type | The type of the body, with its character set or its part boundary. |
| Content-Transfer-Encoding | How the bytes of a part were turned into text, for example base64. |
Two limits keep these lines readable. RFC 5322 says lines must not pass 998 characters and should stay under 78. Long headers get folded onto a new line that starts with a space or tab. Received lines show this most in an EML file.
Read the route from the bottom. Every server adds its Received line on top of the others. The bottom line comes from the first server to take the message, and the top line from the last. To trace a message, start at the bottom and read up. A sender can fake lines at the bottom, so trust only the lines your own mail provider added.
Lines that begin with X- are extras added by mail programs or servers. Their meaning depends on who added them. Some mark spam scores. Others record which app wrote the message. Servers that check senders also add an Authentication-Results line with verdicts for SPF, DKIM and DMARC, when the server checks them.
How Do Attachments Fit Inside an EML File? MIME builds a tree of parts inside one text file
MIME splits the body into parts. A boundary string marks where one part ends and the next begins, so a plain text EML file can carry PDFs and photos.
Plain RFC 5322 text was built for short lines of ASCII. That was fine in 1982. It broke when people wanted to send photos, spreadsheets and messages in Hindi, Japanese or Arabic. MIME arrived in 1996 and fixed this without touching the core format. It lets an EML file say, in headers, what every piece is and how it was written down.
Boundaries and parts
A message with attachments declares Content-Type: multipart/mixed and names a boundary string. The string can be up to 70 characters long and must not appear inside any part, as RFC 2046 lays out. Every part opens with two hyphens and the boundary. The last boundary gets two more hyphens at its end.
Content-Type: multipart/mixed; boundary="BOUNDARY-1"
--BOUNDARY-1
Content-Type: text/plain; charset=UTF-8
Hi Ben, the invoice is attached.
--BOUNDARY-1
Content-Type: application/pdf; name="invoice.pdf"
Content-Disposition: attachment; filename="invoice.pdf"
Content-Transfer-Encoding: base64
JVBERi0xLjQK...
--BOUNDARY-1--Every part has its own small header block, then an empty line, then its content. The skeleton above has two parts: the message text and a PDF named invoice.pdf. A message with five attachments has six parts.
The three multipart types
| Type | What it does |
|---|---|
| multipart/mixed | Joins a body to its attachments. Most EML files with files inside use this type at the top. |
| multipart/alternative | Holds the same content in more than one version, like plain text and HTML. The reader shows the last version it understands. |
| multipart/related | Ties an HTML body to the pictures it shows. Every picture gets a Content-ID that the HTML points to. |
Why text and attachments look like code
Every part can name a Content-Transfer-Encoding. The five legal values are 7bit, 8bit, binary, quoted-printable and base64. Mail apps use base64 for files and quoted-printable for text that has only a few non-ASCII letters. The MIME encoding rules in RFC 2045 define all five.
Headers get their own trick. A subject with an accent is wrapped as an encoded word, so Café menu travels as =?UTF-8?Q?Caf=C3=A9_menu?=. The charset sits between the first two question marks, the letter Q or B names the method and the text follows. RFC 2047 covers the rules.
A message can hold a message.
A forwarded email attached as a file uses the media type message/rfc822. That is the same type that names an EML file itself, so an EML file can sit inside another EML file.
What Do 470 Sample EML Files Show? Where we got them, and which languages and encodings they use
We checked 470 unique sample EML files from five open-source test collections. Most text was English, 79 files used a legacy character set and only 134 began with a From line.
The samples come from the test suites of open-source mail libraries. Their authors wrote some of them by hand and saved others from real mail. We did not export any of them from Gmail, Outlook or Apple Mail. We removed duplicates, so every EML file in the count is different.
| Sample set | Files | What it adds |
|---|---|---|
| MimeKit test set | 215 | A 1990s mailbox plus MIME compliance tests |
| Ruby mail set | 98 | Mixed charsets, with Japanese and Korean mail |
| Flanker set | 98 | Bounces, spam complaints, attachments and 58 DKIM test messages |
| CPython email set | 47 | Hand-built MIME edge cases |
| mailparser set | 12 | Parser test messages |
We downloaded all five collections in October 2026. We read every file with the Python 3.13 email package and counted the headers, parts, encodings and parser warnings. The oldest message in the MimeKit mailbox is from 1991.
Languages and charsets in the sample EML files
Most body text was English. Language detection failed too often on short test text, so we counted character set names and writing scripts instead. A charset name tells you which language family the sender had in mind.
| Charset | Language family | Files |
|---|---|---|
| UTF-8 | Any language | 42 |
| ISO-8859-1 | Western European | 56 |
| ISO-2022-JP or Shift_JIS | Japanese | 8 |
| EUC-KR or KS C 5601 | Korean | 5 |
| KOI8-R | Russian | 5 |
| ISO-8859-8 | Hebrew | 4 |
| ISO-8859-2 | Central European | 4 |
| ISO-8859-3 | South European | 2 |
| ISO-8859-7 | Greek | 1 |
| Big5 | Traditional Chinese | 1 |
One EML file can name more than one charset, so the rows overlap. The decoded text showed Latin, Cyrillic, Hangul, Japanese kana, Han and Hebrew scripts. Python decoded every file without an error. One file named a charset, x-unknown, that no program knows.
A Hindi, Arabic and Thai test we built ourselves
No file in the five collections held Arabic, Hindi or Thai. So we wrote seven short test messages with the Python email package, every one with a UTF-8 subject. The package wrapped the subject as a base64 encoded word, and all seven decoded back to the exact text. The body stayed plain UTF-8 text.
| Script | Subject in a mail app | Subject line in the EML file |
|---|---|---|
| Hindi | मासिक चालान |
=?utf-8?b?4KSu4KS+4KS44KS/4KSVIOCkmuCkvuCksuCkvuCkqA==?=
|
| Arabic | فاتورة أكتوبر |
=?utf-8?b?2YHYp9iq2YjYsdipINij2YPYqtmI2KjYsQ==?=
|
| Japanese | 10月の請求書 |
=?utf-8?b?MTDmnIjjga7oq4vmsYLmm7g=?=
|
| Chinese | 十月发票 |
=?utf-8?b?5Y2B5pyI5Y+R56Wo?=
|
| Russian | Счёт за октябрь |
=?utf-8?b?0KHRh9GR0YIg0LfQsCDQvtC60YLRj9Cx0YDRjA==?=
|
| Thai | ใบแจ้งหนี้เดือนตุลาคม |
=?utf-8?b?4LmD4Lia4LmB4LiI4LmJ4LiH4Lir4LiZ4Li14LmJ4LmA4LiU4Li34Lit?=
|
| Emoji | Invoice paid ✅ |
Invoice paid =?utf-8?b?4pyF?=
|
Read the first column and the last column side by side. A text editor shows the last one, and a mail app decodes it into the first. That gap explains most garbled subject lines in an EML file.
What the counts say about EML files
Read the counts with care. Many of these EML files were written to be broken, so 11 percent is an upper bound for this set and not for your mailbox. The counts show what mail apps must handle, not how common any case is in daily mail.
Repeat the check on your own EML files
Python reads any EML file in a few lines. Replace message.eml with your file name. The code prints the content type, the charsets and any defects.
import email, email.policy
raw = open("message.eml", "rb").read()
msg = email.message_from_bytes(raw, policy=email.policy.default)
print(msg.get_content_type())
print([part.get_content_charset() for part in msg.walk()])
print([type(d).__name__ for d in msg.defects])What Does Our Expert Say About EML Files? A note from Neeraj Singh on what goes wrong most often
When an EML file looks broken, try a second app before you repair or convert anything. The file is rarely the problem.
Expert insight
“Most EML problems I see are not broken files. The message is fine and the app is the problem. If a mail app shows garbled text or hides an attachment, open the same EML file in Thunderbird or a plain text editor before you do anything else. Read the Content-Type and charset lines first, because a wrong character set is the usual cause of garbled text. Only 11 percent of the files in our sample set had a structural defect. Try a second app before you convert or repair anything.”
A 1993 test message that parsers still keep
One of the samples is a demo message from Mark Crispin, dated February 1993. Its own text says it exists to exercise MIME software. It packs messages inside message/rfc822 parts, including one that Nathaniel Borenstein wrote in 1991. The nesting goes six levels deep. It carries audio, images and PostScript. The EML file weighs 1.8 MB.
Flanker keeps a copy as its torture.eml test message, and MimeKit keeps another inside its mailbox file. A reader that survives it handles most real mail.
Try a second app first. Mail apps are forgiving readers, but they forgive different things. If an EML file fails in one app, open it in another before you call it damaged.
How Do You Open an EML File? Routes for Windows, Mac and Linux, plus viewers
Double-click your EML file to open it in your default mail app, or drag it into Thunderbird, Apple Mail or new Outlook. A text editor also works and needs no mail app at all.
You have more than one route, and the app routes cost nothing. Choose the one that fits your machine. To read one message, the app you already own is the fastest way to open an EML file.
On Windows
Windows may ask which app should handle EML files the first time you open one. New Outlook is the route Microsoft documents. The Microsoft guide to opening EML files gives three ways to do it.
- Open new Outlook, then open File Explorer and select the EML file.
- Drag the file onto the reading pane in Outlook. The message opens as if it had just arrived.
- Or right-click the file, choose Open with and select Outlook (new).
- If a double-click opens the wrong app, change the default app for .eml in Windows settings.
Thunderbird is the free option for every system. Open it and select File, then Open, then Saved Message. Choose your EML file. The message opens in its own window with all its attachments listed.
On a Mac
Apple Mail opens an EML file when you double-click it. The message shows in its own window, and you can drag it into a mailbox to keep a copy. Thunderbird for Mac works as it does on Windows. For a quick look at raw text, open the EML file in TextEdit.
On Linux, Android and the web
Thunderbird works on Linux and opens EML files the same way. KMail, the mail app from the KDE project, also reads and writes EML files. Phone support varies by app and by version, so test before you rely on it. A computer is the dependable route.
Gmail on the web is the odd one out. It can give you an EML file, but it cannot open one you already have. Google says plainly that you need a desktop mail client for that, as Google’s own instructions note.
Apps and viewers that open an EML file
Dedicated EML viewers
When you need to view many EML files at once, or have no mail app on the machine, a dedicated viewer saves time. These are the three viewers this site lists.
Why Will an EML File Not Open? Four causes, and only one of them is the file
When an EML file will not open, check the app, the name, the text encoding and the size, in that order. Only the last check points to a damaged EML file.
Most failures come from the setup around the file. An EML file is plain text, and plain text rarely breaks. Work through four causes before you blame the sender.
A five-step check
- Check the size. An EML file of 0 KB holds no message.
- Show file extensions and confirm the name ends in .eml, not .eml.txt.
-
Open the file in Notepad. If it starts with lines like
From:orReceived:, it is a real message. - Open it in Thunderbird with File, Open, Saved Message. If it opens there, the problem was your default app.
- Export or download the message again from the original mailbox, and compare the sizes.
If the file opens but attachments are missing, scroll to the end of the text. A healthy multipart EML file ends with the boundary and two hyphens. A file that stops short lost its last parts, and no app can bring them back.
Wrong page? If the file opens fine and you need a different format, jump to the conversion steps.
Can You Read an EML File Without a Mail App? Yes, in any text editor, plus one command for encoded parts
Yes. Open the EML file in Notepad, TextEdit or any other editor. Headers and plain text show as written, and only encoded parts need decoding.
A text editor is the quickest test for an EML file. It shows what the message really holds, with no mail app between you and the data. It also works on locked-down computers where you cannot install anything.
- Right-click the EML file and choose Open with, then Notepad or TextEdit.
- Find the first empty line. Everything above it is headers, and everything below it is the body.
-
Search for
Content-Type. Every match starts a new part of the message. -
Search for
filename=to find the name of every attachment.
The plain text part reads like an ordinary note. An HTML part reads like web code, because it is. If a message has both, the HTML part comes after the plain text one, as the multipart rules say.
Decode an attachment by hand
An attachment in an EML file is a long block of letters and numbers under a Content-Transfer-Encoding: base64 line. A PDF starts with JVBERi0, because every PDF begins with the characters %PDF-. Copy the block, from the line after the empty line to the next boundary, into a new text file. Then decode it with one command. Base64 is not encryption, and anyone can reverse it.
# Linux
base64 --decode attachment.txt > invoice.pdf
# Mac
base64 -D -i attachment.txt -o invoice.pdf
# Windows
certutil -decode attachment.txt invoice.pdfQuoted-printable text is easier. A code like =E2=80=99 is one curly apostrophe written as three bytes. An equals sign at the very end of a line is a soft break that joins two lines back into one. Most mail apps undo both for you.
Treat a decoded file as a new file. Decoding creates a real PDF, document or program on your disk. Scan it with your antivirus before you open it.
Is It Safe To Open an EML File? The file is text, and the risk is what it carries
Reading an EML file in a text editor is safe. The risk starts when a mail app loads remote images or when you launch an attachment.
An EML file is text, and text cannot execute by itself. That makes an EML file calmer to handle than a program. The danger sits in what the message carries and in how far you trust it.
Servers that check senders add an Authentication-Results line. A pass for SPF, DKIM and DMARC is a good sign. A fail is a reason to stop. Missing results prove nothing, because a saved EML file may have lost them or never had them.
A safe routine for unknown files
- Open the file in a text editor first and read the From, Return-Path and Subject lines.
- Open it in a mail app only if the headers look right, and keep remote images off.
- Do not click links in the body. Type the address of the site yourself.
- Save any attachment to a folder and scan it before you open it.
- Be wary of double endings like invoice.pdf.exe. The last ending is the real one.
One more point helps in legal and support work. An EML file holds the original headers, which makes it stronger evidence than a screenshot. Keep the original untouched and work on a copy. Record a SHA-256 hash of it when proof matters, because the hash shows later that no byte changed. An EML file alone does not prove who wrote the message, since headers can be forged. Back it up with server logs or provider records.
How Does an EML File Differ From MSG, EMLX, MBOX and PST? Three hold one message and two hold many
The EML file is the portable one. It holds a single message as open text, so any mail app can read it. MSG and EMLX are single-message formats tied to one vendor, while MBOX and PST hold many messages.
The email world has more file endings than most people expect. Four of them show up next to the EML file again and again. The table puts all five side by side so you can see what every format holds and who made it.
| Format | What it holds | Made for | Plain text? |
|---|---|---|---|
| EML | One message | Any mail app, under an open standard | Yes |
| MSG | One message | Microsoft Outlook, in a binary format | No |
| EMLX | One message | Apple Mail, with a byte count line and an XML list added | Mostly |
| MBOX | Many messages | Unix mail and Thunderbird, one file per folder | Yes |
| PST | A full mailbox | Outlook, with mail, contacts and calendar | No |
Read the detail pages when you need more. The Outlook MSG format covers Microsoft’s message file. The Apple Mail EMLX format covers the Apple variant. The MBOX mailbox files page explains how many messages share one file. The Outlook PST data files page covers the full mailbox container.
You share one message, keep proof of what was said or move one email between two mail apps.
You back up thousands of messages, keep folder trees or need calendar items and contacts too.
What an EML file does not keep. It holds one message and nothing around it. Folders, read flags, labels, stars and conversation view belong to your mail app and usually stay behind. The delivery envelope, the Bcc list and your provider’s rules are missing too. File dates show when the EML file was saved, not when the message was sent.
Size is one more point. Base64 encodes three bytes as four characters, and line breaks add a little more. An attachment grows by about 37 percent inside an EML file, so a 10 MB PDF adds roughly 13.7 MB.
Wrong page? If you hold an entire mailbox and not one message, start with the full-mailbox PST guide or the offline OST guide.
How Do You Save an Email as an EML File? Gmail, Thunderbird and Apple Mail do it in a few clicks
Gmail, Thunderbird, Apple Mail and new Outlook can all write an EML file in a few clicks. Check the Save As list in classic Outlook, because its options differ by version.
Saving takes under a minute, and the result is a copy. The message stays in your mailbox. Choose your client and follow its steps.
In Gmail
- Go to Gmail on your computer and open the message.
- Select More near the top of the message.
- Select Download message. Your browser saves a file that ends in .eml.
This is the route in Google’s Gmail steps. Google names the format EML there, so the EML file you get is the standard one. It saves one message. A Google Takeout export of a full account arrives as MBOX files and not as separate EML files.
In Thunderbird
- Select the message in the list.
- Open the File menu, then Save As, then File.
- Choose a folder, keep the .eml ending and select Save.
In Apple Mail
Select the message, then choose File, Save As and Raw Message Source. Mail writes one EML file. You can also drag the message from the list to a folder or the desktop. To save several messages at once, select them all and drag the group. Dragging a conversation makes a separate file for every message in it.
In Outlook
New Outlook for Windows saves a message through More actions, then Save as, as Microsoft’s save guide shows. Classic Outlook differs by version, so look for .eml in its Save As list. If it is missing, save the message from Thunderbird or Apple Mail instead.
Where did your EML file come from?
Your operating system does not make an EML file. A mail app, a webmail site, an export tool or a script does. A file on a Mac may come from Apple Mail, Outlook, Thunderbird or a Gmail download in Safari. Note the app, the save method and the account type, because those three tell you what the file can hold.
Two look-alikes fool people. An .emlx file is Apple Mail’s own storage format and not an export. A message file in a Thunderbird Maildir folder holds the same kind of text but may have no .eml ending.
Name the file before you forget. Mail apps name the file after the subject, and many messages share a subject. Start the name with the date, for example 2026-10-09 Contract reply.eml, so a folder sorts in time order.
How Do You Convert an EML File to PDF, MSG or MBOX? Three targets, and what to watch for in every one
Print to PDF for one message. Drag the EML file into Outlook and save it as MSG for Outlook users. Use an importer or converter for MBOX, because joining EML files by hand breaks the format.
Converting always makes a copy in the new format. Your original EML file stays as it was. Keep it, because it holds the headers that other formats may drop.
Check a sample before you trust a big batch. Compare message counts, dates, senders, attachments and inline pictures. MSG can hold Outlook-only properties, and a converter cannot invent data the EML file never had. For evidence or signed mail, hash the originals before you convert.
EML to PDF
- Open the EML file in Thunderbird or Outlook.
- Select Print and choose Microsoft Print to PDF or Save as PDF as the printer.
- Save the PDF and check that the headers you need are on the page.
- Save the attachments separately, because a printed PDF does not carry them.
EML to MSG
Open classic Outlook, then drag the EML file into a mail folder. Outlook builds a copy of the message there. Open it, choose File, then Save As and select Outlook Message Format. The result is an MSG file.
EML to MBOX
It is tempting to join EML files with a copy command. Do not. An MBOX file needs a From line before every message, and any body line that starts with From must be escaped. A raw join leaves messages fused together. Use Thunderbird with an import tool built for the job.
For many EML files at once, or for targets like PST, a dedicated converter saves hours. The EML conversion page lists the routes this site covers. The MBOX conversion page covers MBOX files in the same way.
A converter converts. It reads your EML files and writes new files in another format. It never changes the originals. If a tool offers to edit them in place, decline.
What Is the EML File Format Made Of? Specification, and the facts we could check
An EML file follows RFC 5322 for the message and the MIME documents from RFC 2045 on for the parts. The extension adds nothing of its own, and that is the point.
This section is for readers who want the specification and not the how-to. Skip it if you only need to open an EML file. Every fact below traces to a document you can read yourself, and the source list sits at the end.
| Property | Value |
|---|---|
| Extension | .eml |
| Media type |
message/rfc822, defined in RFC 2046 section 5.2.1
|
| Message standard | RFC 5322, published in October 2008. It replaced RFC 2822, which replaced RFC 822. |
| Part standard | MIME, in RFC 2045 and its sister documents. RFC 2047 covers non-ASCII text in headers. |
| Structure | Header fields, one empty line, then the body |
| Required headers |
Date and From only
|
| Line length | At most 998 characters, with 78 or fewer recommended, not counting the line break |
| Line ending | Carriage return and line feed (CRLF) |
| Transfer encodings | 7bit, 8bit, binary, quoted-printable and base64 |
| File signature | None. The first bytes are whatever the first header is. |
| Maintained by | The Internet Engineering Task Force (IETF) |
About the file signature
You may see 46 72 6F 6D 3A 20 listed as the signature of an EML file. Those bytes spell From: . They match many files, but no standard requires them. A message that starts with Received: or Date: is just as valid, so use the signature as a hint and not as proof.
What we left out
We did not list a registry record for the media type or a version number, because we could not confirm either one against a primary source. The page says what it can check and nothing more.
Sources checked
The RFC 5322 text for message rules and line limits. The RFC 2045 text for encodings. The RFC 2046 text for boundaries and the media type. The RFC 2047 text for encoded words. Google’s Gmail guide, Microsoft’s Outlook guide and the Microsoft Save as steps for the app steps.
Frequently Asked Questions About EML Files
What is an EML file?
An EML file is one email message saved as plain text. It holds the headers, the body and any attachments of that message. The format follows RFC 5322, with MIME for attachments. Mail apps like Thunderbird, Apple Mail and Outlook can open an EML file.
How do I open an EML file?
Double-click the EML file to open it in your default mail app. On Windows you can also drag it onto the reading pane in new Outlook, or use Open with. Thunderbird opens it through File, Open, Saved Message on every system. A text editor works too.
Can Gmail open an EML file?
No. Gmail on the web can give you an EML file through More, then Download message, but it cannot open one you already have. Google says you need a desktop mail client for that. Thunderbird is a free choice.
Can I open an EML file in Notepad?
Yes. Right-click the EML file, choose Open with and select Notepad or TextEdit. You see the headers, then an empty line, then the body. Attachments show up as long blocks of encoded text.
Can I edit an EML file?
You can, because it is plain text. Change the body or a header in any editor and save it. Keep the original safe, though. Edits to signed content can break DKIM checks and make the EML file weak as evidence.
Is an EML file safe to open?
The file is text, so a text editor is safe. An EML file cannot execute by itself. The risk sits in remote images in the HTML body and in attachments. Keep remote images off, check the sender in the headers and scan every attachment before you open it.
What is the difference between EML and MSG?
An EML file is an open text format for one message. MSG is the Outlook message format and is binary. Any mail app reads EML. MSG is built for Outlook, and other apps need help to read it.
What is the difference between EML and PST?
An EML file holds one message. A PST file is an Outlook data file that holds a full mailbox, with mail, contacts and calendar items. PST is binary and needs Outlook or a converter. EML is plain text and keeps no folders, labels or flags.
Does an EML file contain attachments?
It can. Attachments live inside the same EML file as encoded text, usually base64. The file is split into parts by a boundary string. Save the message again if attachments are missing, because a cut-off file loses its last parts.
How do I convert an EML file to PDF?
Open the EML file in Thunderbird or Outlook, select Print and choose Save as PDF or Microsoft Print to PDF. Check that the headers you need are on the page. Save attachments separately, because the PDF will not carry them.
Why does my EML file show codes like =E2=80=99?
That is quoted-printable encoding. The code =E2=80=99 stands for one curly apostrophe written as three bytes. A mail app decodes it for you. A text editor shows it raw, and so does a reader that guesses the wrong character set for an EML file.
How big is an EML file?
An EML file is the size of the message text plus its attachments. Base64 makes attachments about 37 percent larger. A 10 MB PDF therefore adds roughly 13.7 MB to the file. A message with no attachments is usually a few kilobytes. The format sets no single size limit, and real limits come from mail servers, apps and file systems.
Still Stuck With an EML File? Six routes out, depending on what went wrong
Start with the four causes. The default app and a changed name explain most cases.
Go to the PDF, MSG and MBOX steps. Bulk jobs have their own tools, listed below.
Does your file end in .emlx and not .eml? That is the Apple Mail variant, with an extra byte count line at the start. The Apple Mail .emlx guide shows how to read it.
Is it an .msg file from Outlook? The binary MSG guide explains that format and how to open it.
Do you have an entire mailbox and not one message? Read about the Thunderbird MBOX format for Unix mail, or the Outlook OST file for offline copies.
Do you have many EML files to convert at once? Use the bulk EML conversion tools listed on this site. They read EML files and write new ones.
Is the text garbled even in a text editor? Check the Content-Type line and the encoding rules in the section on parts. A wrong character set is the usual cause.
Is it a file type you do not know at all? Browse the file extension resource library, or tell us about it on the submit a file type page.