“根据验证程序，远程证书无效。”使用Gmail SMTP服务器

我得到这个错误:

根据验证过程，远端证书无效。

每当我试图在我的c#代码中使用Gmail的SMTP服务器发送电子邮件时。有人能给我指出解决这个问题的正确方向吗?

下面是堆栈跟踪…

at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
at System.Net.TlsStream.CallProcessAuthentication(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.Mail.SmtpConnection.Flush()
at System.Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at BulkEmail.frmemail.mailsending(String toaddress, String fromaddress, String fromname, String subject, String pwd, String attachements, String mailmessage, String htmlmessage, Int32 i, Int32 j, String replytoaddress)

当前回答

还没有人指出明显的，如果你想安全地调试SSL问题，那么总是使用这种方法:

#if DEBUG
    ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
#endif

即使您不小心提交了代码，它也不会在发布模式下编译。

2021-06-02 21:37:29

其他回答

警告:不要在产品代码中使用此代码!

作为一种解决方法，您可以关闭证书验证。只有在确认由于错误的证书而引发错误时才这样做。

在调用smtpclient.Send()之前调用这个方法:

[Obsolete("Do not use this in Production code!!!",true)]
static void NEVER_EAT_POISON_Disable_CertificateValidation()
{
    // Disabling certificate validation can expose you to a man-in-the-middle attack
    // which may allow your encrypted message to be read by an attacker
    // https://stackoverflow.com/a/14907718/740639
    ServicePointManager.ServerCertificateValidationCallback =
        delegate (
            object s,
            X509Certificate certificate,
            X509Chain chain,
            SslPolicyErrors sslPolicyErrors
        ) {
            return true;
        };
}

2009-09-06 20:00:24

您可以通过在证书无效时询问用户是否想继续来改进代码。你想继续吗?如下:

ServicePointManager.ServerCertificateValidationCallback = 
    new RemoteCertificateValidationCallback(ValidateServerCertificate);

并添加一个这样的方法:

public static bool ValidateServerCertificate(object sender,X509Certificate certificate,X509Chain chain,SslPolicyErrors sslPolicyErrors)
{
    if (sslPolicyErrors == SslPolicyErrors.None)
        return true;
    else
    {
        if (System.Windows.Forms.MessageBox.Show("The server certificate is not valid.\nAccept?", "Certificate Validation", System.Windows.Forms.MessageBoxButtons.YesNo, System.Windows.Forms.MessageBoxIcon.Question) == System.Windows.Forms.DialogResult.Yes)
            return true;
        else
            return false;
    }
}

2011-10-31 15:50:30

在Amazon Linux EC2虚拟机上运行dotnet核心web应用程序时遇到此错误。原来我们已经有一段时间没有运行sudo yum update来修补这个服务器了，并且安装在机器上的根/中间证书已经过期了。(具体来说，本期从2021-09-30开始。)

我们运行这个命令来更新certs，然后重新启动dotnet进程:

Sudo yum更新ca-certificates

对于类似的问题，AWS支持人员进一步向我们指出了这篇支持文章:为什么我在EC2实例上收到Let's Encrypt证书的证书过期错误?

2021-11-04 23:14:14

您确定您使用的SMTP服务器地址正确吗?

smtp.google.com和smtp.gmail.com都可以工作，但是SSL证书颁发给了第二个。

2012-12-17 22:53:36

我的问题是在Windows 2003服务器，当调用AuthenticateAsClient。上面的解决方案(例如绕过ServicePointManager.ServerCertificateValidationCallback)不起作用。

原来这是Windows 2003中的一个bug，并且有一个热修复:

"使用加密API的应用程序无法在Windows Server 2003中验证X.509证书"