/// <summary>
        /// Create and submit an email message to one or more email addresses.
        /// </summary>
        /// <param name="to">Required parameter: A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="type">Required parameter: Specifies the type of email to be sent</param>
        /// <param name="subject">Required parameter: The subject of the mail. Must be a valid string.</param>
        /// <param name="message">Required parameter: The email message that is to be sent in the text.</param>
        /// <param name="mfrom">Optional parameter: A valid address that will send the email.</param>
        /// <param name="cc">Optional parameter: Carbon copy. A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="bcc">Optional parameter: Blind carbon copy. A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="attachment">Optional parameter: A file that is attached to the email. Must be less than 7 MB in size.</param>
        /// <return>Returns the string response from the API call</return>
        public string CreateSendEmail(
            string to,
            Models.TypeEnum type,
            string subject,
            string message,
            string mfrom      = null,
            string cc         = null,
            string bcc        = null,
            string attachment = null)
        {
            Task <string> t = CreateSendEmailAsync(to, type, subject, message, mfrom, cc, bcc, attachment);

            APIHelper.RunTaskSynchronously(t);
            return(t.Result);
        }
        /// <summary>
        /// Create and submit an email message to one or more email addresses.
        /// </summary>
        /// <param name="to">Required parameter: A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="type">Required parameter: Specifies the type of email to be sent</param>
        /// <param name="subject">Required parameter: The subject of the mail. Must be a valid string.</param>
        /// <param name="message">Required parameter: The email message that is to be sent in the text.</param>
        /// <param name="mfrom">Optional parameter: A valid address that will send the email.</param>
        /// <param name="cc">Optional parameter: Carbon copy. A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="bcc">Optional parameter: Blind carbon copy. A valid address that will receive the email. Multiple addresses can be separated by using commas.</param>
        /// <param name="attachment">Optional parameter: A file that is attached to the email. Must be less than 7 MB in size.</param>
        /// <return>Returns the string response from the API call</return>
        public async Task <string> CreateSendEmailAsync(
            string to,
            Models.TypeEnum type,
            string subject,
            string message,
            string mfrom      = null,
            string cc         = null,
            string bcc        = null,
            string attachment = null)
        {
            //the base uri for api requests
            string _baseUri = Configuration.BaseUri;

            //prepare query string for API call
            StringBuilder _queryBuilder = new StringBuilder(_baseUri);

            _queryBuilder.Append("/email/sendemails.json");


            //validate and preprocess url
            string _queryUrl = APIHelper.CleanUrl(_queryBuilder);

            //append request with appropriate headers and parameters
            var _headers = new Dictionary <string, string>()
            {
                { "user-agent", "APIMATIC 2.0" }
            };

            //append form/field parameters
            var _fields = new List <KeyValuePair <string, Object> >()
            {
                new KeyValuePair <string, object>("To", to),
                new KeyValuePair <string, object>("Type", Models.TypeEnumHelper.ToValue(type)),
                new KeyValuePair <string, object>("Subject", subject),
                new KeyValuePair <string, object>("Message", message),
                new KeyValuePair <string, object>("From", mfrom),
                new KeyValuePair <string, object>("Cc", cc),
                new KeyValuePair <string, object>("Bcc", bcc),
                new KeyValuePair <string, object>("Attachment", attachment)
            };

            //remove null parameters
            _fields = _fields.Where(kvp => kvp.Value != null).ToList();

            //prepare the API call request to fetch the response
            HttpRequest _request = ClientInstance.Post(_queryUrl, _headers, _fields, Configuration.BasicAuthUserName, Configuration.BasicAuthPassword);

            //invoke request and get response
            HttpStringResponse _response = (HttpStringResponse)await ClientInstance.ExecuteAsStringAsync(_request).ConfigureAwait(false);

            HttpContext _context = new HttpContext(_request, _response);

            //handle errors defined at the API level
            base.ValidateResponse(_response, _context);

            try
            {
                return(_response.Body);
            }
            catch (Exception _ex)
            {
                throw new APIException("Failed to parse the response: " + _ex.Message, _context);
            }
        }