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How to Convert an MBOX File to PDF — With Attachments and a Table of Contents

Convert an MBOX file to one PDF with attachments, a cover page, and a table of contents. Clear steps for Gmail, Thunderbird, and Apple Mail exports.

An MBOX file can hold years of your mail in one place. That is useful, but it is hard to read or share. Most people cannot open it without a mail app.

This guide shows you how to turn it into one neat PDF. The PDF keeps your mail in date order. It keeps attachments with the right emails. It also adds a cover page and a contents list.

You can use our MBOX to PDF converter to do the job in your browser. You add the file, pick a few simple choices, and save the PDF. The steps below walk you through the whole job.

What an MBOX file is

An MBOX file is one plain text file that holds many emails. Plain text means you can open it with simple tools. The emails sit one after the other in a long line.

Each email starts with a special line. That line starts with the word From and a space. Mail apps use that line to find where each email starts. They also use it to find where each email ends.

Where MBOX files come from

Gmail Takeout gives you MBOX files. Takeout is the Google tool that lets you download your data. When you export Gmail mail, you get one big MBOX file.

Thunderbird also stores mail in this format. Thunderbird is a free mail app for your computer. Apple Mail can export mailboxes in this format too. Apple Mail is the mail app on Mac computers.

What MBOX is not

An MBOX file is not a folder of loose files. It is one file with all the emails joined together. You cannot just pull one email out by hand. You need a tool that can split the file with care.

MBoxToPDF does not open PST files directly. A PST file is a different store used by Outlook. If you have a PST file, export it to MBOX first. Your mail app can often do that export for you.

Why one merged PDF works better

You could make one PDF for each email. That sounds tidy at first. But a mailbox with two thousand emails gives you two thousand files. No one wants to open files one by one.

One merged PDF keeps the whole story in one file. You can scroll through the mail in order. You can search the whole set with one search. You can print it or share it as one item.

A merged volume also has page numbers that make sense. Each page says Page x of y at the bottom. That means page three of nine hundred, for example. Anyone can cite an exact page and others can find it.

A volume you can hand to someone else

A client, a lawyer, or a family member can read a PDF. They do not need your mail app or your account. They just open the file and start to read.

The contents list shows each email and its start page. A reader can jump to the right place fast. PDF also looks the same on most devices. That is one reason why PDF works for long-term email archives for so many teams.

Before you start

Find your MBOX file and note where it sits. It may be inside a Takeout zip file. A zip file is a packed file that holds other files. If your export came as a zip, unpack it first.

Make a copy of the file before you start. Keep the first copy in a safe place. That way your source stays safe no matter what.

Check the file size before you upload it. Big files need a plan with a big enough limit. The table below shows the limit for each plan.

How to convert step by step

The job has five short steps. Each step takes just a few clicks. Read all five steps before you start. Then work through them in order.

1. Open the converter page in your browser.
2. Add your MBOX file or add several files at once.
3. Choose date order or group the mail by thread.
4. Add any extra files you want on paid plans.
5. Start the conversion and wait for it to finish.
6. Download the merged PDF when it is ready.
7. Open the PDF and check the first few pages.

A thread is a chain of emails on one topic. It holds the first mail and all the replies. Grouping by thread keeps the whole talk together. Date order puts the oldest mail first across the whole set.

You can add more than one file in one job. MBoxToPDF accepts mbox, eml, and msg files together. That helps if your archive is split in parts. The tool merges all of them into one volume.

If you exported mail from Gmail, the steps are the same. A short guide shows how to turn a Gmail Takeout export into PDF with no extra tools.

Pick the right order for your job

Date order is best for a clear time line. It shows what was said first, next, and last. It suits most archives, handovers, and reviews.

Thread order is best when talks matter most. A long talk stays in one block. You can read the full talk from start to end. You do not have to hunt for replies across the file.

What you get in the volume

The finished PDF is more than a stack of pages. It is built like a small book. Each part has a clear job to do. Here is what sits inside the volume, in order.

• A cover page at the very front.
• A table of contents with start pages.
• Your emails in the order you picked.
• Attachment pages right after their emails.
• A page count on every single page.

The cover page tells the reader what the file holds. The contents list names each email in order. Together they make a long file feel short. A new reader can find their way at once.

The header block on each email

Each email starts with a header block. A header block is the small set of facts at the top. It tells you who sent the mail and when. It shows these six facts for each email.

• From, which names the sender of the email.
• To, which names the main person it went to.
• Cc, which names others who got a copy.
• Date, which shows when the email was sent.
• Subject, which is the title of the email.
• Message-ID, which is a unique code for that email.

The Message-ID helps you match emails across files. No two emails share the same code. If you need to prove two copies are the same mail, check this code.

The header block sits right above the mail text. So the facts and the text never get split up. You always know who wrote what you read.

Attachments in the volume

Attachments stay with the email they came with. An attachment is a file sent along with an email. Photos, forms, and signed sheets are common examples.

Some attachments also become pages in the PDF. PDF files become pages right after their email. Images become pages right after their email too. Plain text files become pages as well.

Every attachment is also saved inside the PDF. It is kept as its first, original file. A reader can open it from inside the PDF. They get the true file, not just a picture of it.

Office files work in a different way. Word, Excel, and PowerPoint files do not become pages. They are listed with their email instead. They are saved inside the PDF as files.

On paid plans they also go in the ZIP file. A ZIP file is a packed file you can download. It holds one PDF for each email. It also holds the attachment files in full.

One rule covers very large attachments. A single attachment over 25 MB is not saved inside the PDF. It is still in the ZIP file in full. It is also noted in the CSV index, which is explained below.

Plans and limits

Each plan has a file size limit. Each plan also has a mail count limit. Only a good conversion counts toward your monthly total. A failed job does not use up your allowance.

You can compare the plans to see all the details side by side. The short table below shows the key limits. Use it to match your job to the right plan.

The Free plan gives you the merged PDF only. It suits a small test or a small mailbox. You can try the full flow with no cost at all.

Starter and Pro add two useful extras. You get a metadata CSV index with your PDF. You also get a ZIP with one PDF per email. A CSV file is a simple table you can open in a sheet app.

The CSV index has one row for each email. Each row lists the date and the sender. It lists who got the mail and who got a copy. It lists the subject and the attachment names. It also lists the message code and the thread code.

Pro adds two more tools for large jobs. You can filter mail by date range before export. You can also filter by keyword before export. The keyword is matched in the subject, sender, and body.

Pro also adds Bates numbering for formal sets. Bates numbering stamps a code on each page. You set the prefix and the first number. The stamp runs across the whole volume in order. It sits in the footer of each page, cover included.

On Pro, the cover page prints the full Bates range. The CSV also notes the first and last Bates number for each email. Those two columns are called bates_start and bates_end. They help you cite a mail by its page stamps.

Common problems and what they mean

Most conversions run with no trouble at all. But old mail can hold a few traps. Here are the ones people meet most often.

The file is very large

A Takeout file can be many gigabytes in size. That is more than most plans allow in one job. Split the source mailbox into smaller exports first. Most mail apps let you export one folder at a time.

You can also filter the job on the Pro plan. Pick a date range that holds the mail you need. Leave out years that no one needs to read. Smaller jobs convert faster and read better.

A message is corrupt or locked

Some old messages are corrupt, which means damaged. Some are encrypted, which means locked with a key. The tool cannot show their text in the PDF.

These messages are not dropped in silence. They are flagged in the CSV index instead. You can see which mail had the problem. You can then deal with it in another way.

A message has no date

A few old messages have no send date at all. The tool cannot sort them by date. So it puts them at the end of the volume. They stay in the same order as in the source file.

Check the end of the volume for these mails. They are still in the PDF in full. They just sit after all the dated mail. The CSV index shows them there as well.

Tips for very large mailboxes

Large jobs go well with a bit of prep. A few small steps save a lot of time. Use these tips when your mailbox holds years of mail.

• Export one folder or one year at a time.
• Remove mail you do not need before you start.
• Use a date filter to cut the job down.
• Keep a copy of the source file at all times.
• Check the first volume before you do the rest.

Start with the most key folder first. Convert it and check the result with care. If the volume looks right, do the next folder. This way you catch problems while jobs are small.

Store the PDF and the CSV index together. The index helps you find a mail fast. The PDF gives you the full text to read. Together they make a strong, simple archive.

How your files are handled

Your files travel over HTTPS, a safe link. HTTPS scrambles data while it moves online. The files are then processed on the server. Processing just means the conversion work itself.

Files are deleted on their own after 24 hours. You do not need to ask for this. The service does not read mail for other uses. It does not sell data or train models on your mail.

Download your results soon after the job ends. Save them in a place you control. Then you hold the only copy that lasts.

Final checks before you share the PDF

Open the PDF and read the cover page first. Check that the title and dates look right. Then jump to a few pages in the middle. Check that headers and text look clean and clear.

Search for a word you know is in the mail. Check one email that had an attachment. Make sure the attachment pages sit right after it. If all of that looks right, your volume is done.

References

• Library of Congress — Preserving Your Digital Memories: Keeping Personal Electronic Mail