Actually, it is listed, but Apple doesn’t really fully describe what it does.
Archive Mailbox
Create an archive of your mailbox to back up important messages or to transfer your mail to another computer.
Yeah, so you can create an archive of your mail. But Apple doesn’t use a proprietary archiving method. This actually is just a simple export to the standard mbox format. Woo!
In Tiger, the previous version of OS X, Apple switched from using the mbox format–which stores emails in one monstrous file–to a single-email-per-file system using an emlx extension so that Spotlight could search the emails individually. But this also left people wanting to switch from Tiger’s mail (or simply backup their emails) out in the cold rain. Nearly every other email system uses the mbox format, so you’d have to employ the dodgy method of converting emlx to mbox with Cosmic Soft’s aptly named emlx to mbox converter. It worked. Uh… sometimes. There were always gitches.
It’s nice to see this unannounced feature in Leopard Mail!








