Free online MBX to EML converter

What the MBX format is

In the Internet context, MBX is the mailbox format used by Qualcomm Eudora and some Eudora-compatible mail tools. An MBX file contains a sequence of email messages, usually separated by Eudora mailbox markers, rather than one independently readable message per file.

Eudora may also create a matching .toc table-of-contents file. The TOC stores indexes and message-list information; the MBX file contains the actual message data. Keep both files while copying or recovering a mailbox, although a converter generally reads the MBX content directly.

What the EML format is

EML is a MIME email-message format based on Internet message headers and body data. Each EML file normally represents one complete message, including headers such as From, To, Date, and Subject, plus plain-text, HTML, and MIME attachment parts.

Mail applications such as Mozilla Thunderbird, Windows Mail, Apple Mail, and many archive and e-discovery programs can open or import EML files. EML is preferable when messages must be opened individually, copied between mail clients, searched by file, or stored with their original MIME attachments.

How to convert MBX to EML

Using the converter on 101convert.com

1. Open the MBX converter on 101convert.com. The service can be used free without installing software.
2. Select the Eudora .mbx file. If the mailbox has a related .toc file, keep it available, but upload it only if the converter requests it.
3. Choose EML as the output format and start the conversion.
4. Download the generated archive or files. A mailbox containing multiple messages should produce multiple EML files, not one EML file containing the entire mailbox.
5. Open several converted files in an email client and check headers, HTML formatting, and attachments before deleting the source.

Do not upload confidential, regulated, or legally sensitive mail to an online service. Use a local converter for those messages.

Using desktop conversion software

A dedicated mail-conversion utility such as Aid4Mail can read Eudora MBX mailboxes and export each message as EML without requiring Eudora itself.

1. Make a working copy of the MBX file and preserve the original mailbox and its .toc file.
2. In Aid4Mail, select Eudora or MBX as the source format and browse to the mailbox copy.
3. Choose EML as the destination format and select an empty output folder.
4. Enable the option that exports individual messages if the program offers both single-mailbox and per-message output.
5. Run the export, then inspect a sample of the resulting EML files in Thunderbird or another EML-capable client.

Menu names vary by Aid4Mail version, so use the source-format identification shown by the program rather than renaming the file to another extension.

Quality and compatibility limitations

MBX is not one universal mailbox specification. The source must be identified as a Eudora-style MBX; changing an unrelated file's extension to .mbx will not make it convertible.

Conversion normally preserves message headers, text, HTML parts, and MIME attachments. It may not preserve Eudora-specific read, replied, label, priority, or mailbox-index state because EML has no standard fields for all client-specific flags. The Eudora .toc file is an index, not a substitute for the MBX message data.

If messages contain damaged separators, nonstandard encodings, truncated MIME parts, or missing attachment data, some messages may be skipped or exported with altered formatting. Compare the message count before and after conversion, and verify representative messages with attachments and non-ASCII characters.