def method_missing(name, *args, &block)
      #:nodoc:
      # Only take the structured fields, as we could take _anything_ really
      # as it could become an optional field... "but therin lies the dark side"
      field_name = Utilities.underscoreize(name).chomp("=")
      if Mail::Field::KNOWN_FIELDS.include?(field_name)
        if args.empty?
          header[field_name]
        else
          header[field_name] = args.first
        end
      else
        super # otherwise pass it on
      end
      #:startdoc:
    end
def method_missing(name, *args, &block)
      #:nodoc:
      # Only take the structured fields, as we could take _anything_ really
      # as it could become an optional field... "but therin lies the dark side"
      field_name = Utilities.underscoreize(name).chomp("=")
      if Mail::Field::KNOWN_FIELDS.include?(field_name)
        if args.empty?
          header[field_name]
        else
          header[field_name] = args.first
        end
      else
        super # otherwise pass it on
      end
      #:startdoc:
    end
Method Missing in this implementation allows you to set any of the
 standard fields directly as you would the "to", "subject" etc.

 Those fields used most often (to, subject et al) are given their
 own method for ease of documentation and also to avoid the hook
 call to method missing.

 This will only catch the known fields listed in:

  Mail::Field::KNOWN_FIELDS

 as per RFC 2822, any ruby string or method name could pretty much
 be a field name, so we don't want to just catch ANYTHING sent to
 a message object and interpret it as a header.

 This method provides all three types of header call to set, read
 and explicitly set with the = operator

 Examples:

  mail.comments = 'These are some comments'
  mail.comments #=> 'These are some comments'

  mail.comments 'These are other comments'
  mail.comments #=> 'These are other comments'


  mail.date = 'Tue, 1 Jul 2003 10:52:37 +0200'
  mail.date.to_s #=> 'Tue, 1 Jul 2003 10:52:37 +0200'

  mail.date 'Tue, 1 Jul 2003 10:52:37 +0200'
  mail.date.to_s #=> 'Tue, 1 Jul 2003 10:52:37 +0200'


  mail.resent_msg_id = '<1234@resent_msg_id.lindsaar.net>'
  mail.resent_msg_id #=> '<1234@resent_msg_id.lindsaar.net>'

  mail.resent_msg_id '<4567@resent_msg_id.lindsaar.net>'
  mail.resent_msg_id #=> '<4567@resent_msg_id.lindsaar.net>'