Bug 963331 - [B2G][email]Recieved emails can be moved to 'Local Drafts' folder.

I don't think the use of folder.selectable here works out in certain edge cases.  See https://bugzilla.mozilla.org/show_bug.cgi?id=963331#c14 for more context.  With things as they exist, this may be okay, but I'd want a comment on selectable here explaining how it might break in the future or what its current assumptions are.