我正在为学校项目开发邮件客户端。我已设法使用C＃中的SmtpClient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。我已尝试在EnableSsl上设置true到SmtpClient，但这没有任何区别。
这是我用来创建SmtpClient并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
有谁知道为什么我会收到此错误？
答案 0 :(得分：23)
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据无效，请确保您使用的是有效的 GMAIL 电子邮件/密码组合。< / p>
您可能需要阅读here作为工作示例。
编辑：好的，这是我当时编写和测试的内容，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，可以使用类似的SO文章here
答案 1 :(得分：22)
尝试运行：
mozroots --import --ask-remove
（仅限bash或Mono命令提示符，如果它在Windows上）。然后再次运行代码。
修改
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）。
答案 2 :(得分：4)
我认为，您需要验证用于建立SSL连接的服务器证书.....
使用以下代码发送带有验证服务器证书的邮件.....
this.client = new SmtpClient(_account.SmtpHost, _account.SmtpPort);
this.client.EnableSsl = _account.SmtpUseSSL;
this.client.Credentials = new NetworkCredential(_account.Username, _account.Password);
try
{
// Create instance of message
MailMessage message = new MailMessage();
// Add receivers
for (int i = 0; i < email.Receivers.Count; i++)
message.To.Add(email.Receivers[i]);
// Set sender
message.From = new MailAddress(email.Sender);
// Set subject
message.Subject = email.Subject;
// Send e-mail in HTML
message.IsBodyHtml = email.IsBodyHtml;
// Set body of message
message.Body = email.Message;
//validate the certificate
ServicePointManager.ServerCertificateValidationCallback =
delegate(object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{ return true; };
// Send the message
this.client.Send(message);
// Clean up
message = null;
}
catch (Exception e)
{
Console.WriteLine("Could not send e-mail. Exception caught: " + e);
}
导入System.Security.Cryptography.X509Certificates命名空间以使用ServicePointManager
答案 3 :(得分：3)
此代码适用于我，尝试将其粘贴到LinqPad，编辑邮件地址和密码并告诉我们您的看法：
var client = new System.Net.Mail.SmtpClient("smtp.gmail.com", 587);
client.EnableSsl = true;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("me@gmail.com", "xxxxxxx");
try
{
// Create instance of message
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
// Add receiver
message.To.Add("me@gmail.com");
// Set sender
// In this case the same as the username
message.From = new System.Net.Mail.MailAddress("me@gmail.com");
// Set subject
message.Subject = "Test";
// Set body of message
message.Body = "En test besked";
// Send the message
client.Send(message);
// Clean up
message = null;
}
catch (Exception e)
{
Console.WriteLine("Could not send e-mail. Exception caught: " + e);
}
答案 4 :(得分：3)
您需要在Gmail帐户中启用两步验证并创建应用密码（https://support.google.com/accounts/answer/185833?hl=en）。使用新的应用密码替换密码后，它应该可以正常工作。
Credentials = new System.Net.NetworkCredential("your email address", "your app password");
答案 5 :(得分：1)
我在6个月的工作后于2013年5月开始使用GMail。 Mono项目的Using Trusted Roots Respectfully文档提供了有关解决方案的指导。我选择了选项＃1：
ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
我的服务电子邮件在没有警告的情况下停止工作是太具有破坏性了。
2016年8月26日更新：用户Chico建议完成ServerCertificateValidationCallback回调的完整实现。我没有测试过。
ServicePointManager.ServerCertificateValidationCallback = MyRemoteCertificateValidationCallback;
bool MyRemoteCertificateValidationCallback(System.Object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) {
bool isOk = true;
// If there are errors in the certificate chain, look at each error to determine the cause.
if (sslPolicyErrors != SslPolicyErrors.None) {
for (int i=0; i<chain.ChainStatus.Length; i++) {
if (chain.ChainStatus [i].Status != X509ChainStatusFlags.RevocationStatusUnknown) {
chain.ChainPolicy.RevocationFlag = X509RevocationFlag.EntireChain;
chain.ChainPolicy.RevocationMode = X509RevocationMode.Online;
chain.ChainPolicy.UrlRetrievalTimeout = new TimeSpan (0, 1, 0);
chain.ChainPolicy.VerificationFlags = X509VerificationFlags.AllFlags;
bool chainIsValid = chain.Build ((X509Certificate2)certificate);
if (!chainIsValid) {
isOk = false;
}
}
}
}
return isOk;
}