class Mail::AddressList

:nodoc:

def addresses_grouped_by_group 

def addresses_grouped_by_group
  addresses.select(&:group).group_by(&:group)
end

def initialize(string)

a.group_names #=> ["My Group"]
a.addresses #=> [#a = AddressList.new(list)
list = 'ada@test.lindsaar.net, My Group: mikel@test.lindsaar.net, Bob ;'

RFC822. It also handles all obsolete versions in those RFCs.
Mail::AddressList requires a correctly formatted group or mailbox list per RFC2822 or

It can supply all addresses in an array, or return each address as an address object.

string.
AddressList provides a way to query the groups and mailbox lists of the passed in

emails passed into Mail.
Mail::AddressList is the class that parses To, From and other address fields from 
def initialize(string)
  address_list = Parsers::AddressListsParser.parse(string)
  @addresses = address_list.addresses.map { |a| Address.new(a) }
  @group_names = address_list.group_names
end