C#

public static SmtpClient create_SMTPClient(smtp_credentials smtpC)
        {
            var smtpClient = new SmtpClient();
            var smtpSection = (SmtpSection)ConfigurationManager.GetSection("system.net/mailSettings/smtp");
            if (smtpSection == null)
            {
                smtpClient.UseDefaultCredentials = false;
                smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;

<pre>
            var smtpCredentials = new System.Net.NetworkCredential() {
                UserName = smtpC.smtp_AccountName,
                Password = smtpC.smtp_Password
            };

            smtpClient.Credentials = smtpCredentials;
            smtpClient.Host = smtpC.smtp_ServerUrl;
            smtpClient.Port = smtpC.smtp_PortNumber;
            smtpClient.EnableSsl = smtpC.smtp_PortNumber == 587 ? true : false;
            smtpClient.Timeout = 250000;
        }

        // Shift the encryption level higher for gMail and others
        if (smtpClient.Port == 587)
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
        if (smtpClient.Port == 443)
            ServicePointManager.ServerCertificateValidationCallback += RemoteCertificateValidation_Callback;

        return smtpClient;
    }

    public static async Task<SendEmailCompletedEventArgs> sendEmailAsync(SmtpClient smtpClient, MailMessage message, int retryCount)
    {
        int currentTry = 0;
        while ((currentTry < retryCount))
        {
            try
            {
                await smtpClient.SendMailAsync(message);
                return new SendEmailCompletedEventArgs(null, false, null, currentTry);
            }
            catch (Exception ex)
            {
                currentTry++;
                if ((currentTry >= retryCount))
                {
                    return new SendEmailCompletedEventArgs(ex, true, null, currentTry);
                }
            }

        }

        //  Code should never reach here, but without this line you'll get a BC42105 warning:
        return new SendEmailCompletedEventArgs(null, true, null, currentTry);
    }</pre>