How to Export Maildir to PST Format

You moved off a Linux mail server, or inherited a backup, and now a folder of thousands of odd-named files sits on your desktop. Outlook cannot open them. Maildir keeps every message as its own file with no extension, so Outlook sees nothing to import. Your mail is safe inside those files, and three methods below turn Maildir to PST.

What is Maildir and why can't Outlook open it?

Maildir is a mail storage format that keeps every message as its own file inside a folder. Outlook cannot open it because Outlook reads PST, its own archive format, and Maildir has no index or database for Outlook to load. Postfix, Exim, Dovecot, Courier, qmail and OpenSMTPD all store mail that way, and so do clients like Mutt and Evolution.

Maildir folders hold three subfolders:

• tmp holds messages during delivery.
• new holds delivered messages that no mail app has opened yet.
• cur holds messages that were opened or seen.

Message names are unique strings built from timestamp, process ID and host name. When messages move to cur, mail apps add suffixes like :2,S after colons. Digit 2 is format version and letters after it are flags: S means seen, R replied and F flagged.

Colons cause real trouble. Windows does not allow colons in file names, so plain copies to NTFS fail or rename files. One Unix and Linux Stack Exchange user who moved Maildir to Windows asked whether Mutt supports another character. Answer: no. Mutt and NeoMutt hard code colons.

How to prepare Maildir files before you convert Maildir to PST?

Copy your Maildir first. Work on copies so new mail does not land in live folders mid export. Then check four things:

1. Copy your full Maildir folder from your server with WinSCP, scp or a zip archive. Keep cur, new and tmp together.
2. Look for dot folders like .Sent, .Drafts and .Trash. Dovecot and Courier store subfolders as hidden dot folders beside cur and new.
3. Zip your copy on your server before moving it, so colons in names do not break transfers.
4. Check disk space on Windows. Your PST needs room equal to your mail.

Real forum posts show why preparation matters. One Edaboard user asked how to move Maildir mailboxes from a Linux server to PST while keeping folder structure and metadata, and one reply pointed to a paid converter, since Outlook has no Maildir import.

How to convert Maildir to PST manually with Outlook?

Rename every message to .eml, drag files into an Outlook folder and export that folder to PST. It works for small mailboxes. Messages are plain RFC 822 text, so Outlook opens renamed .eml files as email.

Rename Maildir messages to EML

Run it on your Linux server for one folder. It copies messages from cur and new, swaps colons and commas for underscores and adds .eml:

mkdir -p ~/export/Inbox
for f in ~/Maildir/cur/* ~/Maildir/new/*; do
  cp "$f" ~/export/Inbox/"$(basename "$f" | tr ':,' '__').eml"
done

Repeat for every dot folder, changing Inbox and your source path. Then zip your export folder and copy it to Windows.

Import EML files and export PST

1. Open classic Outlook and create folders for your mail.
2. Open your export folder in File Explorer and select all .eml files with Ctrl+A.
3. Drag them into your Outlook folder. Wait until all messages appear.
4. Select File, Open & Export, Import/Export.
5. Choose Export to a file, then Outlook Data File (.pst).
6. Select your folder, tick Include subfolders, choose a save location and select Finish.

The catch: you repeat steps folder by folder, rebuild folder structure by hand and lose Maildir flags like seen and replied. A mailbox with dozens of folders takes hours. Other vendors list a similar Thunderbird, EML and Outlook path and warn that manual conversion is slow and error prone.

How to export Maildir to PST through IMAP?

If your mail server still runs, add your account to Outlook over IMAP and export PST from there. IMAP shows server folders inside Outlook, so you skip file renaming.

1. Confirm that IMAP is on for your server, such as Dovecot.
2. In classic Outlook, select File, Add Account and enter your IMAP server, port and login.
3. Wait for folders to sync. Large mailboxes take time.
4. Select File, Open & Export, Import/Export, Export to a file, Outlook Data File (.pst).
5. Select your IMAP account, tick Include subfolders and finish.

It fails when your server is gone, and that is exactly when people hold only a Maildir backup. It also needs live logins. Our guide on how to download IMAP emails from server covers sync settings.

Steps to convert Maildir to PST with software

1. Install Corbett Maildir Backup Software on a Windows PC and start it.
2. Select Open, then Email Data Files, then Maildir Files.
3. Select Select Folders icon and browse to your Maildir folder. You need no mail server login.
4. Preview mail in Content, Message Header, Properties and Raw Message views.
5. Select Export and choose PST.
6. Set filters by date, sender, subject or file size if needed, choose a destination and select Save.

It keeps your original folder hierarchy, attachments and contacts. It reads several Maildir folders in one run and sets no file size limit. It does not need Outlook installed. Work from a copy of your Maildir when your server is still live.

Need other formats from one source? Corbett Email Converter Tool converts Maildir along with PST, MBOX, EML and MSG files. Only need sender addresses? See how to extract email addresses from Maildir.

Which way to export Maildir to PST is best?

Use manual EML for one or two folders, IMAP while your server runs and software for full mailboxes.

Moving to another mail client later? See how to open MBOX file for Thunderbird mail, or import EML to Windows 10 Mail.

Why does export of Maildir files fail?

Windows rejects Maildir file names

Colons are illegal in Windows file names. Rename files on your server first, or zip your Maildir before copying. Software that reads Maildir folders directly skips renaming.

Outlook shows no mail after drag and drop

Files without .eml extension do not open as messages. Add .eml, close Outlook dialogs and drag again. Tmp holds unfinished deliveries, so skip it.

Subfolders are empty

Maildir subfolders sit beside cur and new as dot folders. Export every dot folder, and check its own cur and new inside.

PST is too large

Outlook 2010 and later cap Unicode PST files at 50 GB by default. Split big Maildirs by date. Our guide on PST size limits and fixes lists every limit.

See Wikipedia's Maildir article for full naming rules.

What to do after you convert Maildir to PST?

Open your PST in Outlook, then check folder counts against your Maildir. Select File, Open & Export, Open Outlook Data File. For a full walkthrough, see how to import PST to Outlook. If Outlook refuses your file, see PST is not an Outlook data file. Want to check mail without Outlook? Open PST file shows how.

Questions about Maildir to PST