smtp电子邮件发送请求有时会失败

Question

我在c#中使用以下代码，

string Subject = "test12";     
    MailMessage mail = new MailMessage();
    mail.To.Add(item.ToString());
    mail.From = new MailAddress(EmailUserName);
    mail.Subject = Subject;
    mail.Body = PopulateBody();       
    mail.IsBodyHtml = true;
    SmtpClient client = new SmtpClient(EmailHost, EmailPort);        
    client.EnableSsl = true;
    NetworkCredential credentials = new NetworkCredential(EmailUserName, EmailPassword);
    client.UseDefaultCredentials = false;
    client.Credentials = credentials;
    client.Send(mail);

我在客户端发送（邮件）方法中出错

我尝试过的：

System.Security.Authentication.Authentication异常：对SSPI的调用失败，请参阅内部异常。--->System.ComponentModel.Win32异常：不支持请求的函数---内部异常堆栈跟踪结束---位于System.Net.Security.SslState.StartSendAuthResetSignal（ProtocolToken消息，AsyncProtocolRequest asyncRequest，异常异常）

Answer 1

我会先尝试不进行身份验证，以检查是否会出现不同的错误，然后尝试不使用ssl。

    protected bool NotifyByMail(string server, string strFrom, string strTo, string strSubject, string strBodyText, bool isBodyTextHtml = false)
    {
        if (string.IsNullOrEmpty (server)
            || string.IsNullOrEmpty (strFrom)
            || string.IsNullOrEmpty (strTo)
            || string.IsNullOrEmpty (strSubject)
            || string.IsNullOrEmpty (strBodyText))
            return false;
        try {
            MailAddress from = new MailAddress (strFrom);
            MailAddress to = new MailAddress (strTo);
            MailMessage message = new MailMessage (from, to);
            message.Subject = strSubject;
            message.Body = strBodyText;
            message.IsBodyHtml = isBodyTextHtml;
            SmtpClient client = new SmtpClient (server);
        // Include credentials if the server requires them.
        //client.Credentials = new System.Net.NetworkCredential ("********", "*******");// System.Net.CredentialCache.DefaultNetworkCredentials;
            client.Send (message);
            return true;
        }
        catch (Exception exception) {
                    // TODO ErrorHandling
        }
        return false;
    }