MBOXCL2 is one of the MBOX family of related file formats used for holding collections of electronic mail messages. See MBOX for a description of the syntax.
Like MBOXCL but unlike MBOXO and MBOXRD, MBOXCL2 does not scan for "From " lines to determine message separator points. Instead, each MBOXCL2 message contains a "Content-Length:" header that denotes the length of the message body, after transformation, in octets. This header is added to the message when it is added to the mailbox, and used to locate the start of each next message.
Unlike MBOXCL, MBOXO and MBOXRD, MBOXCL2 does not use "From " quoting at all so no greater-than signs (">") are prepended to or striped from the "From " lines.