class Mail::Body

def sort_parts!

sort_parts! is also called from :encode, so there is no need for you to call this explicitly

set with :set_sort_order.
Allows you to sort the parts according to the default sort order, or the sort order you 
def sort_parts!
  order = @part_sort_order
  @parts = @parts.sort do |a, b|
    # OK, 10000 is arbitrary... if anyone actually wants to explicitly sort 10000 parts of a
    # single email message... please show me a use case and I'll put more work into this method,
    # in the meantime, it works :)
    a_order = order.index(a[:content_type].string.downcase) || 10000
    b_order = order.index(b[:content_type].string.downcase) || 10000
    a_order <=> b_order
  end
end