MBOX or mailbox file contains email messages in text form. Along with messages, attachments are also stored by MBOX files. Numerous applications support MBOX file format such as Mozilla Thunderbird, Apple Mail, Netscape, Entourage, Eudora, etc.
MBOX File Format
MBOX file format represents encoded information intended for storage in a computer file. It saves messages in a concatenated format where each message is stored after another, starting with “From” header. MBOX file formats were non-standardized for a long time. After 2005, the application/mbox was standardized as RFC 4155.
Reading MBOX messages
To read MBOX files, a correct application installation is required on the user system. Any From¬¬¬¬¬ ¬_line marks the starting of the message. Once the reader finds MBOX message, it extracts an envelope sender and delivery date out of the From_line and then it reads it until the next From_line or end of the file, whichever comes first.
Encoding Considerations
The content of MBOX file becomes irreversibly intermix when an email received contained an MBOX file as attachment and is saved into another MBOX file. To avoid this, messaging systems must encode the mbox database with non-transparent encoding (like BASE64 or Quoted-Printable) whenever such an object is transferred through messaging protocols.