C# 如何使用 .NET Framework 通过 SSL SMTP 发送电子邮件？
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How can I send emails through SSL SMTP with the .NET Framework?
提问by Idriss
Is there a way with the .NET Framework to send emails through an SSL SMTP server on port 465?
.NET Framework 有没有办法通过端口 465 上的 SSL SMTP 服务器发送电子邮件？
The usual way:
通常的方法：
System.Net.Mail.SmtpClient _SmtpServer = new System.Net.Mail.SmtpClient("tempurl.org");
_SmtpServer.Port = 465;
_SmtpServer.EnableSsl = true;
_SmtpServer.Credentials = new System.Net.NetworkCredential("username", "password");
_SmtpServer.Timeout = 5000;
_SmtpServer.UseDefaultCredentials = false;
MailMessage mail = new MailMessage();
mail.From = new MailAddress(from);
mail.To.Add(to);
mail.CC.Add(cc);
mail.Subject = subject;
mail.Body = content;
mail.IsBodyHtml = useHtml;
_SmtpServer.Send(mail);
times out:
超时：
System.Net Verbose: 0 : [1024] SmtpClient::.ctor(host=ssl0.ovh.net, port=465)
System.Net Information: 0 : [1024] Associating SmtpClient#64923656 with SmtpTransport#44624228
System.Net Verbose: 0 : [1024] Exiting SmtpClient::.ctor() -> SmtpClient#64923656
System.Net Information: 0 : [1024] Associating MailMessage#17654054 with Message#52727599
System.Net Verbose: 0 : [1024] SmtpClient#64923656::Send(MailMessage#17654054)
System.Net Information: 0 : [1024] SmtpClient#64923656::Send(DeliveryMethod=Network)
System.Net Information: 0 : [1024] Associating SmtpClient#64923656 with MailMessage#17654054
System.Net Information: 0 : [1024] Associating SmtpTransport#44624228 with SmtpConnection#14347911
System.Net Information: 0 : [1024] Associating SmtpConnection#14347911 with ServicePoint#51393439
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Socket(InterNetwork#2)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Socket()
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Socket(InterNetworkV6#23)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#23264094::Socket()
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Connect(20:465#337754884)
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Connect()
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Close()
System.Net.Sockets Verbose: 0 : [1024] Socket#23264094::Dispose()
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#23264094::Close()
System.Net Information: 0 : [1024] Associating SmtpConnection#14347911 with SmtpPooledStream#14303791
System.Net.Sockets Verbose: 0 : [1024] Socket#26756241::Receive()
System.Net.Sockets Verbose: 0 : [2404] Socket#26756241::Dispose()
System.Net.Sockets Error: 0 : [1024] Exception in the Socket#26756241::Receive - A blocking operation was interrupted by a call to WSACancelBlockingCall
System.Net.Sockets Verbose: 0 : [1024] Exiting Socket#26756241::Receive() -> 0#0
System.Net Error: 0 : [1024] Exception in the SmtpClient#64923656::Send - Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall.
System.Net Error: 0 : [1024] at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.DelegatedStream.Read(Byte[] buffer, Int32 offset, Int32 count)
at System.Net.BufferedReadStream.Read(Byte[] buffer, Int32 offset, Int32 count)
at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)
at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)
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)
System.Net Verbose: 0 : [1024] Exiting SmtpClient#64923656::Send()
System.Net Information: 0 : [1024] Associating MailMessage#49584532 with Message#19699911
I googled around and found that System.Net.Mail supports connections on port 587 (default port for Explicit SSL that starts unencrypted then issues a STARTDLS then switches to an Encrypted connection: RFC 2228), but doesn't support Implicit SSL (entire connection is wrapped in an SSL layer)...
我搜索了一下，发现 System.Net.Mail 支持端口 587 上的连接（显式 SSL 的默认端口未加密启动然后发出 STARTDLS 然后切换到加密连接：RFC 2228），但不支持隐式 SSL（整个连接包裹在 SSL 层中）...
采纳答案by Andrew Siemer
Here is an example of how to send email through GMail which also uses SSL/465. Minor tweaking of the code below should work!
以下是如何通过 GMail 发送电子邮件的示例，该 GMail 也使用 SSL/465。对下面的代码稍作调整应该可以工作！
using System.Web.Mail;
using System;
public class MailSender
{
public static bool SendEmail(
string pGmailEmail,
string pGmailPassword,
string pTo,
string pSubject,
string pBody,
System.Web.Mail.MailFormat pFormat,
string pAttachmentPath)
{
try
{
System.Web.Mail.MailMessage myMail = new System.Web.Mail.MailMessage();
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpserver",
"smtp.gmail.com");
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpserverport",
"465");
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendusing",
"2");
//sendusing: cdoSendUsingPort, value 2, for sending the message using
//the network.
//smtpauthenticate: Specifies the mechanism used when authenticating
//to an SMTP
//service over the network. Possible values are:
//- cdoAnonymous, value 0. Do not authenticate.
//- cdoBasic, value 1. Use basic clear-text authentication.
//When using this option you have to provide the user name and password
//through the sendusername and sendpassword fields.
//- cdoNTLM, value 2. The current process security context is used to
// authenticate with the service.
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate","1");
//Use 0 for anonymous
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendusername",
pGmailEmail);
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendpassword",
pGmailPassword);
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpusessl",
"true");
myMail.From = pGmailEmail;
myMail.To = pTo;
myMail.Subject = pSubject;
myMail.BodyFormat = pFormat;
myMail.Body = pBody;
if (pAttachmentPath.Trim() != "")
{
MailAttachment MyAttachment =
new MailAttachment(pAttachmentPath);
myMail.Attachments.Add(MyAttachment);
myMail.Priority = System.Web.Mail.MailPriority.High;
}
System.Web.Mail.SmtpMail.SmtpServer = "smtp.gmail.com:465";
System.Web.Mail.SmtpMail.Send(myMail);
return true;
}
catch (Exception ex)
{
throw;
}
}
}
回答by Idriss
It works with System.Web.Mail (which is marked as obsolete):
它适用于 System.Web.Mail（已标记为过时）：
private const string SMTP_SERVER = "http://schemas.microsoft.com/cdo/configuration/smtpserver";
private const string SMTP_SERVER_PORT = "http://schemas.microsoft.com/cdo/configuration/smtpserverport";
private const string SEND_USING = "http://schemas.microsoft.com/cdo/configuration/sendusing";
private const string SMTP_USE_SSL = "http://schemas.microsoft.com/cdo/configuration/smtpusessl";
private const string SMTP_AUTHENTICATE = "http://schemas.microsoft.com/cdo/configuration/smtpauthenticate";
private const string SEND_USERNAME = "http://schemas.microsoft.com/cdo/configuration/sendusername";
private const string SEND_PASSWORD = "http://schemas.microsoft.com/cdo/configuration/sendpassword";
System.Web.Mail.MailMessage mail = new System.Web.Mail.MailMessage();
mail.Fields[SMTP_SERVER] = "tempurl.org";
mail.Fields[SMTP_SERVER_PORT] = 465;
mail.Fields[SEND_USING] = 2;
mail.Fields[SMTP_USE_SSL] = true;
mail.Fields[SMTP_AUTHENTICATE] = 1;
mail.Fields[SEND_USERNAME] = "username";
mail.Fields[SEND_PASSWORD] = "password";
System.Web.Mail.SmtpMail.Send(mail);
What is your point of view regarding obsolete namespace usage?
您对过时的命名空间使用有何看法？
回答by Kinze
回答by Bryan Allred
You can also connect via port 465, but due to some limitations of the System.Net.Mail namespace you may have to alter your code. This is because the namespace does not offer the ability to make implicit SSL connections. This is discussed at http://blogs.msdn.com/b/webdav_101/archive/2008/06/02/system-net-mail-with-ssl-to-authenticate-against-port-465.aspx.
您也可以通过端口 465 进行连接，但由于 System.Net.Mail 命名空间的一些限制，您可能需要更改您的代码。这是因为命名空间不提供建立隐式 SSL 连接的能力。这在http://blogs.msdn.com/b/webdav_101/archive/2008/06/02/system-net-mail-with-ssl-to-authenticate-against-port-465.aspx 中进行了讨论。
It is possible to make implicit connections without having to use the now obsolete System.Web.Mail namespace, but you have to access the Microsoft CDO (Collaborative Data Object). I have supplied an example of how to use the CDO in another discussion (GMail SMTP via C# .Net errors on all ports).
无需使用现已过时的 System.Web.Mail 命名空间即可建立隐式连接，但您必须访问 Microsoft CDO（协作数据对象）。我在另一个讨论中提供了一个如何使用 CDO 的示例（GMail SMTP via C# .Net errors on all ports）。
Hope this helps!
希望这可以帮助！
回答by RekhaShanmugam
If any doubt in this code, please ask your questions(Here for gmail Port number is 587)
如果对此代码有任何疑问，请提出您的问题（此处为 gmail 端口号为 587）
// code to Send Mail
// Add following Lines in your web.config file
// <system.net>
// <mailSettings>
// <smtp>
// <network host="smtp.gmail.com" port="587" userName="[email protected]" password="yyy" defaultCredentials="false"/>
// </smtp>
// </mailSettings>
// </system.net>
// Add below lines in your config file inside appsetting tag <appsetting></appsetting>
// <add key="emailFromAddress" value="[email protected]"/>
// <add key="emailToAddress" value="[email protected]"/>
// <add key="EmailSsl" value="true"/>
// Namespace Used
using System.Net.Mail;
public static bool SendingMail(string subject, string content)
{
// getting the values from config file through c#
string fromEmail = ConfigurationSettings.AppSettings["emailFromAddress"];
string mailid = ConfigurationSettings.AppSettings["emailToAddress"];
bool useSSL;
if (ConfigurationSettings.AppSettings["EmailSsl"] == "true")
{
useSSL = true;
}
else
{
useSSL = false;
}
SmtpClient emailClient;
MailMessage message;
message = new MailMessage();
message.From = new MailAddress(fromEmail);
message.ReplyTo = new MailAddress(fromEmail);
if (SetMailAddressCollection(message.To, mailid))
{
message.Subject = subject;
message.Body = content;
message.IsBodyHtml = true;
emailClient = new SmtpClient();
emailClient.EnableSsl = useSSL;
emailClient.Send(message);
}
return true;
}
// if you are sending mail in group
private static bool SetMailAddressCollection(MailAddressCollection toAddresses, string mailId)
{
bool successfulAddressCreation = true;
toAddresses.Add(new MailAddress(mailId));
return successfulAddressCreation;
}
回答by Nil Null
Try to check this free an open source alternative https://www.nuget.org/packages/AIMIt is free to use and open source and uses the exact same way that System.Net.Mail is using To send email to implicit ssl ports you can use following code
尝试检查这个免费的开源替代方案 https://www.nuget.org/packages/AIM它可以免费使用和开源，并且使用与 System.Net.Mail 使用的完全相同的方式将电子邮件发送到隐式 ssl您可以使用以下代码的端口
public static void SendMail()
{
var mailMessage = new MimeMailMessage();
mailMessage.Subject = "test mail";
mailMessage.Body = "hi dude!";
mailMessage.Sender = new MimeMailAddress("[email protected]", "your name");
mailMessage.To.Add(new MimeMailAddress("[email protected]", "your friendd's name"));
// You can add CC and BCC list using the same way
mailMessage.Attachments.Add(new MimeAttachment("your file address"));
//Mail Sender (Smtp Client)
var emailer = new SmtpSocketClient();
emailer.Host = "your mail server address";
emailer.Port = 465;
emailer.SslType = SslMode.Ssl;
emailer.User = "mail sever user name";
emailer.Password = "mail sever password" ;
emailer.AuthenticationMode = AuthenticationType.Base64;
// The authentication types depends on your server, it can be plain, base 64 or none.
//if you do not need user name and password means you are using default credentials
// In this case, your authentication type is none
emailer.MailMessage = mailMessage;
emailer.OnMailSent += new SendCompletedEventHandler(OnMailSent);
emailer.SendMessageAsync();
}
// A simple call back function:
private void OnMailSent(object sender, AsyncCompletedEventArgs asynccompletedeventargs)
{
if (e.UserState!=null)
Console.Out.WriteLine(e.UserState.ToString());
if (e.Error != null)
{
MessageBox.Show(e.Error.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else if (!e.Cancelled)
{
MessageBox.Show("Send successfull!", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
回答by Bob Mc
I'm late to this party but I'll offer my approach for any passersby that might be interested in an alternative.
我迟到了，但我会为任何可能对替代方案感兴趣的路人提供我的方法。
As noted in previous answers, the System.Net.MailSmtpClientclass does not support Implicit SSL. It does support Explicit SSL, which requires an insecure connection to the SMTP server over port 25 in order to negotiate the transport level security (TLS). I blogged about my travails with this subtlety here.
如之前的答案所述，System.Net.MailSmtpClient该类不支持Implicit SSL。它确实支持显式 SSL，这需要通过端口 25 与 SMTP 服务器建立不安全的连接，以便协商传输级别安全性 (TLS)。我在这里用这种微妙的方式在博客上记录了我的痛苦。
In short, SMTP over Implict SSL port 465 requires TLS to be negotiated beforeconnecting to the SMTP server. Rather than write a .Net SMTPS implementation I turned to a utility named Stunnel. It's a small service that will let you redirect traffic on a local port to a remote port via SSL.
简而言之，SMTP over Implict SSL port 465 需要在连接到 SMTP 服务器之前协商 TLS 。我没有编写 .Net SMTPS 实现，而是转向了一个名为Stunnel的实用程序。这是一项小型服务，可让您通过 SSL 将本地端口上的流量重定向到远程端口。
DISCLAIMER: Stunnel uses portions of the OpenSSL library, which recently had a high-profile exploit published in all major tech news media. I believe the latest version uses the patched OpenSSL but please use at your own risk.
免责声明：Stunnel 使用了 OpenSSL 库的一部分，该库最近在所有主要科技新闻媒体上都发布了一个备受瞩目的漏洞利用。我相信最新版本使用修补过的 OpenSSL，但请自担风险。
Once the utility is installed a small addition to the configuration file:
安装该实用程序后，在配置文件中添加一个小内容：
; Example SSL client mode services
[my-smtps]
client = yes
accept = 127.0.0.1:465
connect = mymailserver.com:465
...instructs the Stunnel service to reroute local requests to port 465 to my mail server on port 465. This happens over TLS, which satisfies the SMTP server on the other end.
...指示 Stunnel 服务将本地请求重新路由到端口 465 到我的邮件服务器的端口 465。这是通过 TLS 发生的，它满足另一端的 SMTP 服务器。
Using this utility, the following code will successfully transmit over port 465:
使用此实用程序，以下代码将成功通过端口 465 传输：
using System;
using System.Net;
using System.Net.Mail;
namespace RSS.SmtpTest
{
class Program
{
static void Main( string[] args )
{
try {
using( SmtpClient smtpClient = new SmtpClient( "localhost", 465 ) ) { // <-- note the use of localhost
NetworkCredential creds = new NetworkCredential( "username", "password" );
smtpClient.Credentials = creds;
MailMessage msg = new MailMessage( "[email protected]", "[email protected]", "Test", "This is a test" );
smtpClient.Send( msg );
}
}
catch( Exception ex ) {
Console.WriteLine( ex.Message );
}
}
}
}
So the advantage here is that you can use Implict SSL and port 465 as the security protocol while still using the send mail methods built into the framework. The disadvantage is that it requires the use of a third party service that may not be useful for anything but this specific function.
所以这里的优点是您可以使用隐式 SSL 和端口 465 作为安全协议，同时仍然使用框架中内置的发送邮件方法。缺点是它需要使用第三方服务，除了此特定功能外，该服务可能对任何事情都没有用。
回答by user2584621
For gmail these settings worked for me, the ServicePointManager.SecurityProtocol line was necessary. Because I has setup 2 step verification I needed get a App Password from google app password generator.
SmtpClient mailer = new SmtpClient();
mailer.Host = "smtp.gmail.com";
mailer.Port = 587;
mailer.EnableSsl = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
对于 gmail，这些设置对我有用，ServicePointManager.SecurityProtocol 行是必要的。因为我已经设置了两步验证，所以我需要从谷歌应用密码生成器获取一个应用密码。
SmtpClient mailer = new SmtpClient();
mailer.Host = "smtp.gmail.com";
mailer.Port = 587;
mailer.EnableSsl = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
回答by Cody Ｇ
In VB.NET while trying to connect to Rackspace's SSL port on 465 I encountered the same issue (requires implicit SSL). I made use of https://www.nuget.org/packages/MailKit/in order to successfully connect.
在 VB.NET 中尝试连接到 465 上的 Rackspace 的 SSL 端口时，我遇到了同样的问题（需要隐式 SSL）。为了成功连接，我使用了https://www.nuget.org/packages/MailKit/。
The following is an example of an HTML email message.
以下是 HTML 电子邮件消息的示例。
Imports MailKit.Net.Smtp
Imports MailKit
Imports MimeKit
Sub somesub()
Dim builder As New BodyBuilder()
Dim mail As MimeMessage
mail = New MimeMessage()
mail.From.Add(New MailboxAddress("", c_MailUser))
mail.To.Add(New MailboxAddress("", c_ToUser))
mail.Subject = "Mail Subject"
builder.HtmlBody = "<html><body>Body Text"
builder.HtmlBody += "</body></html>"
mail.Body = builder.ToMessageBody()
Using client As New SmtpClient
client.Connect(c_MailServer, 465, True)
client.AuthenticationMechanisms.Remove("XOAUTH2") ' Do not use OAUTH2
client.Authenticate(c_MailUser, c_MailPassword) ' Use a username / password to authenticate.
client.Send(mail)
client.Disconnect(True)
End Using
End Sub
回答by Luke
I know I'm joining late to the discussion, but I think this can be useful to others.
我知道我加入讨论晚了，但我认为这对其他人有用。
I wanted to avoid deprecated stuff and after a lot of fiddling I found a simple way to send to servers requiring Implicit SSL: use NuGet and add the MailKit packageto the project. (I used VS2017 targetting .NET 4.6.2 but it should work on lower .NET versions...)
我想避免弃用的东西，经过大量的摆弄后，我找到了一种发送到需要隐式 SSL 的服务器的简单方法：使用 NuGet 并将MailKit 包添加到项目中。（我使用了针对 .NET 4.6.2 的 VS2017，但它应该适用于较低的 .NET 版本......）
Then you'll only need to do something like this:
然后你只需要做这样的事情：
using MailKit.Net.Smtp;
using MimeKit;
var client = new SmtpClient();
client.Connect("server.name", 465, true);
// Note: since we don't have an OAuth2 token, disable the XOAUTH2 authentication mechanism.
client.AuthenticationMechanisms.Remove ("XOAUTH2");
if (needsUserAndPwd)
{
// Note: only needed if the SMTP server requires authentication
client.Authenticate (user, pwd);
}
var msg = new MimeMessage();
msg.From.Add(new MailboxAddress("[email protected]"));
msg.To .Add(new MailboxAddress("[email protected]"));
msg.Subject = "This is a test subject";
msg.Body = new TextPart("plain") {
Text = "This is a sample message body"
};
client.Send(msg);
client.Disconnect(true);
Of course you can also tweak it to use Explicit SSL or no transport security at all.
当然，您也可以调整它以使用显式 SSL 或根本不使用传输安全性。
