c# - 发送电子邮件时如何修复 'No connection could be made because the target machine actively refused it' 错误

Question

我正在尝试发送一封简单的测试电子邮件来检查邮件类在 C# 中的工作方式，但是在尝试调用 smtp.send(message); 时我收到以下错误: SocketException:无法建立连接，因为目标机器主动拒绝它 173.194.207.109:587 我已经查看了 wireshark 中的数据包(尽管不可否认我没有理解它们的知识)并且每次我尝试发送电子邮件时谷歌似乎都会发回 [RST, ACK] 数据包。有办法进一步诊断吗？

var fromAddress = new MailAddress("FROM@gmail.com", "FROM NAME");
var toAddress = new MailAddress("TO@gmail.com", "TO NAME");
const string fromPassword = "password";
const string subject = "Subject";
const string body = "Body";

var smtp = new SmtpClient
{
    Host = "smtp.gmail.com",
    Port = 587,
    EnableSsl = true,
    DeliveryMethod = SmtpDeliveryMethod.Network,
    UseDefaultCredentials = false,
    Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
};
using (var message = new MailMessage(fromAddress, toAddress)
{
    Subject = subject,
    Body = body
})
{
    smtp.Send(message);
}    

Answer 1

看起来您可能想要更改您的 port 值，因为您有 EnableSsl = true,

Connect to smtp.gmail.com on port 465, if you're using SSL. (Connect on port 587 if you're using TLS.) Sign in with a Google username and password for authentication to connect with SSL or TLS. Reference

尝试:

var fromAddress = new MailAddress("FROM@gmail.com", "FROM NAME");
var toAddress = new MailAddress("TO@gmail.com", "TO NAME");
const string fromPassword = "password";
const string subject = "Subject";
const string body = "Body";

var smtp = new SmtpClient
{
    Host = "smtp.gmail.com",
    Port = 465, //or try: port = 587, or port = 25
    EnableSsl = true,
    DeliveryMethod = SmtpDeliveryMethod.Network,
    UseDefaultCredentials = false,
    Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
};
using (var message = new MailMessage(fromAddress, toAddress)
{
    Subject = subject,
    Body = body
})
{
    smtp.Send(message);
}

这StackOverflow Answer也可以作为很好的引用使用。