Other VM-supported email folders

[Skip Montanaro]

I help maintain the spam filters on mail.python.org. From
time-to-time, I pull down an mbox file of messages which SpamBayes
scored as "unsure". At the moment, I'm downloading an mbox file which
(uncompressed) is just under 2gb. My normal plan of attack is to just
load it up using vm-visit-file, then sort a sample of the messages
into spam and ham mbox files,  but I fear this large of a file might
bring my Emacs instance to its knees. Are there other supported mail
folder formats which vm understands, perhaps maildir?

Thx,

Skip Montanaro