"The two primary formats for mail storage in Linux and Unix are Mbox and MailDir. There are several other formats out there as well, including MMDF (a close cousin to Mbox), MH (similar to MailDir, but used more in IMAP mail senarios), and BABYL. Other than Mbox and MailDir, most other formats are either deprecated, obsolete, or in very limited use. Hence most end users won't encounter said formats and thus don't need to worry about them. Therefore, we'll only concentrate today on the primary two formats.
"Mbox
"To get started, we'll look at the Mbox format. Mbox is one of those old Unix standards that refuses to die, and for good reasons, as I for one feel it's the better format. And it's not some rusty old relic of days gone by, it's still a format that's in constant development. I believe the current version is 7.0 which incorporates even more new mail features available on the web, as well as improved support for a variety of security systems."
