type local_part = string
type domain = string
type addr_spec = local_part * domain option
class mailbox :
  ?name:string ->
  string list ->
  addr_spec ->
  object
    method name : string
    method route : string list
    method spec : addr_spec
  end
class group :
  string ->
  mailbox list ->
  object method mailboxes : mailbox list method name : string end
type t = [ `Group of group | `Mailbox of mailbox ]
exception Parse_error of int * string
val parse : string -> t list