def get_email_key(response_id, requester=False):
    """
    Returns a formatted key for an email.
    Intended for storing the body of an email.

    :param response_id: id of the response
    :param requester: will the stored content be emailed to a requester?

    :return: the formatted key
        Ex.
            1_requester
            1_agency
    """
    return '_'.join((str(response_id), 'requester' if requester else 'agency'))