But MH is the only format among those supported by c-client (except support for it is so poor that it is unusable in practice) which supports folders having both messages and subfolders.
No, there is also mx format.
It is also "plain text" (and so is preferrable to MBX) and vastly faster than MBOX.
I don't think that you'll find that mh is faster than mbox in general. Some operations (e.g. expunge) may be faster on Linux, but not operations involving many messages (e.g. search).
On UNIX (as opposed to Linux), mh is extremely slow.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
