def create_non_compliance_message(missing_tag_list, vault, event, context):
    """
    Messaging function.

    Structures the outgoing SNS notification format
    """
    missing_tags = ', '.join(missing_tag_list)
    message = "Violation - Glacier Vault is missing required tags!  \n\n"
    message += 'Glacier Vault: ' + vault + '\n'
    message += 'Missing Tag(s): ' + missing_tags + '\n'
    message += 'Account: ' + event["account"] + "\n"
    message += "Region: " + event["detail"]["awsRegion"] + "\n"
    message += "\n\n"
    message += "This notification was generated by the Lambda function " + \
        context.invoked_function_arn
    return message