使用Gmail的SmtpClient

Question

我正在为学校项目开发一个邮件客户端.我已经设法使用SmtpClientC#发送电子邮件.这适用于任何服务器,但它不适用于Gmail.我相信这是因为谷歌使用TLS.我曾尝试设置EnableSsl到true上SmtpClient,但这并不有所作为.

这是我用来创建SmtpClient和发送电子邮件的代码.

this.client = new SmtpClient("smtp.gmail.com", 587);
this.client.EnableSsl = true;
this.client.UseDefaultCredentials = false;
this.client.Credentials = new NetworkCredential("username", "password");

try
{
    // Create instance of message
    MailMessage message = new MailMessage();

    // Add receiver
    message.To.Add("myemail@mydomain.com");

    // Set sender
    // In this case the same as the username
    message.From = new MailAddress("username@gmail.com");

    // Set subject
    message.Subject = "Test";

    // Set body of message
    message.Body = "En test besked";

    // Send the message
    this.client.Send(message);

    // Clean up
    message = null;
}
catch (Exception e)
{
    Console.WriteLine("Could not send e-mail. Exception caught: " + e);
}

这是我尝试发送电子邮件时遇到的错误.

Could not send e-mail. Exception caught: System.Net.Mail.SmtpException: Message could not be sent. ---> System.IO.IOException: The authentication or decryption has failed. ---> System.InvalidOperationException: SSL authentication error: RemoteCertificateNotAvailable, RemoteCertificateChainErrors
  at System.Net.Mail.SmtpClient.<callback>m__4 (System.Object sender, System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Security.Cryptography.X509Certificates.X509Chain chain, SslPolicyErrors sslPolicyErrors) [0x00000] in <filename unknown>:0 
  at System.Net.Security.SslStream+<BeginAuthenticateAsClient>c__AnonStorey7.<>m__A (System.Security.Cryptography.X509Certificates.X509Certificate cert, System.Int32[] certErrors) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslClientStream.OnRemoteCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] errors) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslStreamBase.RaiseRemoteCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] errors) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslClientStream.RaiseServerCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] certificateErrors) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.validateCertificates (Mono.Security.X509.X509CertificateCollection certificates) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.ProcessAsTls1 () [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.Handshake.HandshakeMessage.Process () [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) Mono.Security.Protocol.Tls.Handshake.HandshakeMessage:Process ()
  at Mono.Security.Protocol.Tls.ClientRecordProtocol.ProcessHandshakeMessage (Mono.Security.Protocol.Tls.TlsStream handMsg) [0x00000] in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult) [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult) [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at System.Net.Mail.SmtpClient.Send (System.Net.Mail.MailMessage message) [0x00000] in <filename unknown>:0 
  at P2Mailclient.SMTPClient.send (P2Mailclient.Email email) [0x00089] in /path/to/my/project/SMTPClient.cs:57 

有谁知道为什么我可能会收到此错误？

Answer 1

Gmail的SMTP服务器要求您使用有效的Gmail电子邮件/密码组合对您的请求进行身份验证.您也需要启用SSL.在没有真正能够看到所有变量的转储的情况下,我可以做出的最佳猜测是您的凭证无效,请确保您使用的是有效的GMAIL电子邮件/密码组合.

您可能需要阅读此处的工作示例.

编辑:好的,这是我在那时编写和测试的东西,它对我来说很好用:

public static bool SendGmail(string subject, string content, string[] recipients, string from) {
    if (recipients == null || recipients.Length == 0)
        throw new ArgumentException("recipients");

    var gmailClient = new System.Net.Mail.SmtpClient {
        Host = "smtp.gmail.com",
        Port = 587,
        EnableSsl = true,
        UseDefaultCredentials = false,
        Credentials = new System.Net.NetworkCredential("******", "*****")
    };

    using (var msg = new System.Net.Mail.MailMessage(from, recipients[0], subject, content)) {
        for (int i = 1; i < recipients.Length; i++)
            msg.To.Add(recipients[i]);

        try {
            gmailClient.Send(msg);
            return true;
        }
        catch (Exception) {
            // TODO: Handle the exception
            return false;
        }
    }
}

如果您需要更多信息,那么这里有类似的SO文章

Answer 2

试试这个:

mozroots --import --ask-remove

在你的系统中(只是在bash或Mono命令提示符,如果它在Windows上).然后再次运行代码.

编辑:

我忘了你也应该跑

certmgr -ssl smtps://smtp.gmail.com:465

(并在问题上回答是).这适用于Mono 2.10.8,Linux(带有您的示例).

Answer 3

You need to enable 2-Step Verification in your gmail account and create an app password (https://support.google.com/accounts/answer/185833?hl=en). Once you replace your password with the new app password, it should work.

Credentials = new System.Net.NetworkCredential("your email address", "your app password");