Suppose I turn on the setting for Mail in the iCloud preferences pane. What does this actually do? I've never turned this on; I have a vague memory that I once did, and that bad/weird things happened with my mail (messages getting synced in ways that I didn't want or something). But it's so long ago that I no longer remember, and now I'm wondering if I should just get over it and turn it on.
If this syncs the details of my mail accounts across my OS X / iOS devices, that'd be nice. Does it do anything else?