def add_email_subcommand(input_from_stdin_or_file, selected_address_books):
    """Add a new email address to contacts, creating new contacts if necessary.

    :param input_from_stdin_or_file: the input text to search for the new email
    :type input_from_stdin_or_file: str
    :param selected_address_books: the addressbooks that were selected on the
        command line
    :type selected_address_books: list of address_book.AddressBook
    :returns: None
    :rtype: None

    """
    # get name and email address
    message = message_from_string(input_from_stdin_or_file, policy=SMTP_POLICY)

    print("Khard: Add email address to contact")
    if not message['From'] \
            or not message['From'].addresses:
        print("Found no email address")
        sys.exit(1)

    email_address = message['From'].addresses[0].addr_spec
    name = message['From'].addresses[0].display_name

    print("Email address: %s" % email_address)
    if not name:
        name = input("Contact's name: ")

    # search for an existing contact
    selected_vcard = choose_vcard_from_list(
        "Select contact for the found e-mail address",
        get_contact_list_by_user_selection(selected_address_books, name, True))
    if selected_vcard is None:
        # create new contact
        while True:
            input_string = input("Contact %s does not exist. Do you want "
                                 "to create it (y/n)? " % name)
            if input_string.lower() in ["", "n", "q"]:
                print("Canceled")
                sys.exit(0)
            if input_string.lower() == "y":
                break
        # ask for address book, in which to create the new contact
        selected_address_book = choose_address_book_from_list(
            "Select address book for new contact", config.abooks)
        if selected_address_book is None:
            print("Error: address book list is empty")
            sys.exit(1)
        # ask for name and organisation of new contact
        while True:
            first_name = input("First name: ")
            last_name = input("Last name: ")
            organisation = input("Organisation: ")
            if not first_name and not last_name and not organisation:
                print("Error: All fields are empty.")
            else:
                break
        selected_vcard = CarddavObject.from_user_input(
            selected_address_book,
            "First name : %s\nLast name : %s\nOrganisation : %s" % (
                first_name, last_name, organisation),
            config.get_supported_private_objects(),
            config.get_preferred_vcard_version(),
            config.localize_dates())

    # check if the contact already contains the email address
    for type, email_list in sorted(
            selected_vcard.get_email_addresses().items(),
            key=lambda k: k[0].lower()):
        for email in email_list:
            if email == email_address:
                print("The contact %s already contains the email address %s" %
                      (selected_vcard, email_address))
                sys.exit(0)

    # ask for confirmation again
    while True:
        input_string = input(
            "Do you want to add the email address %s to the contact %s (y/n)? "
            % (email_address, selected_vcard))
        if input_string.lower() in ["", "n", "q"]:
            print("Canceled")
            sys.exit(0)
        if input_string.lower() == "y":
            break

    # ask for the email label
    print("\nAdding email address %s to contact %s\n"
          "Enter email label\n"
          "    vcard 3.0: At least one of home, internet, pref, work, x400\n"
          "    vcard 4.0: At least one of home, internet, pref, work\n"
          "    Or a custom label (only letters" %
          (email_address, selected_vcard))
    while True:
        label = input("email label [internet]: ") or "internet"
        try:
            selected_vcard.add_email_address(label, email_address)
        except ValueError as err:
            print(err)
        else:
            break
    # save to disk
    selected_vcard.write_to_file(overwrite=True)
    print("Done.\n\n%s" % selected_vcard.print_vcard())
Add a new email address to contacts, creating new contacts if necessary.

    :param input_from_stdin_or_file: the input text to search for the new email
    :type input_from_stdin_or_file: str
    :param selected_address_books: the addressbooks that were selected on the
        command line
    :type selected_address_books: list of address_book.AddressBook
    :returns: None
    :rtype: None