What is MBOX File Extension – Its Location & Supportive Applications


MBOX file extension is one of most commonly seen file format that is used over a range of email apps like Thunderbird, Apple Mail, and Entourage. It stores and organizes email messages.

Emailing has become an essential part of any business. But have you ever wondered what happens when you send or receive the email messages? Where exactly are these files saved and especially in what format? There are distinct email platforms to fulfill the need for email communication without any failure. Different kinds of email file formats are available these days to save the email data such as MBOX, PST, OST, OLM, etc.

More Information about MBOX File Format

MBOX file is a plain text file having facility to save emails into 7-bit ASCII text along with other details such as attachments within an encoded format. It actually concatenates multiple email messages into a single file one after another. Each message within this file gets started with "From_" and it winds up with a blank line. First developed for Unix platforms, MBOX file extension made its way into other platforms and has become the most popular file format for storing mailbox data.

Brief Introduction of the MBOX Family

Time to time the file format is updated as per businesses need and all four modified file formats are described here:

Mboxo: When MBOX file format keeps email address of sender as "???@???" then, this file format is said to be Mboxo. The most common email client that uses this file format is Eudora. Integrity of emails within this file format does not remain same as attachments and emails were saved into different folders.

Mboxrd: Other version of the MBOX file format after Mboxo is Mboxrd. This file format for MBOX keeps "From" whether into body of a message or into header. Qmail is a known email client along with Thunderbird, Mozilla, Netscape, etc where this file format is highly used.

Mboxcl: Another version of MBOX is Mboxcl that also comes in mboxcl2 mailbox format, both of these file formats are in use over UNIX 'System V'. This file format contains '>' as a pre-fix to any line of the mail that may be into header or within body.

Mboxcl2: Almost close proximity of Mboxcl to Mboxcl2 makes it little different with act of denoting Content-Length: header as start and end of the message.

Want to Know Where MBOX File is Located?

mbox file location

This is the default location of MBOX files for Mac Mail. Each email application stores the MBOX file at different locations.

Supportive Email Clients that use MBOX File

There are more than 20 email clients that uses MBOX file format as its mailbox storage format.

  • Mozilla Thunderbird
  • Eudora
  • Entourage
  • Apple Mail
  • Mulberry
  • SeaMonkey
  • Spicebird
  • Netscape
  • Pocomail
  • Postbox
  • Claws Mail
  • Google Vault
  • Turnpike
  • The Bat
  • Gyaz Mail
  • Powermail
  • Horde Mail
  • Evolution Mail
  • Sylpheed
  • Opera Mail
  • Sparrow Mail
  • Sparrow Mail
  • Pocomail
  • GNUMail

Multiple backup services also provide email backups in MBOX file format, such as:

Note: Although there are several applications to read MBOX file, some users also wish to open them in non-supported applications such as MS Outlook. In such cases, conversion tool is necessary.