通过 Gmail 在 .NET 中发送电子邮件

请务必使用 ，而不是已弃用的 .使用SSL是一堆乱七八糟的黑客扩展。System.Net.MailSystem.Web.MailSystem.Web.Mail

using System.Net;
using System.Net.Mail;

var fromAddress = new MailAddress("[email protected]", "From Name");
var toAddress = new MailAddress("[email protected]", "To Name");
const string fromPassword = "fromPassword";
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);
}

此外，请转到 Google 帐号>安全页面，然后查看登录 Google >两步验证设置。

• 如果启用，则必须生成一个密码，允许 .NET 绕过两步验证。为此，请单击“登录 Google”>“应用密码”，选择“应用 = 邮件”和“设备 = Windows 计算机”，最后生成密码。在常量中使用生成的密码，而不是标准的 Gmail 密码。fromPassword
• 如果它被禁用，那么你必须打开不太安全的应用程序访问，这是不建议的！因此，最好启用两步验证。

上面的答案是行不通的。您必须设置，否则它将返回“客户端未通过身份验证”错误。此外，设置超时总是一个好主意。DeliveryMethod = SmtpDeliveryMethod.Network

修改后的代码：

using System.Net.Mail;
using System.Net;

var fromAddress = new MailAddress("[email protected]", "From Name");
var toAddress = new MailAddress("[email protected]", "To Name");
const string fromPassword = "password";
const string subject = "test";
const string body = "Hey now!!";

var smtp = new SmtpClient
{
    Host = "smtp.gmail.com",
    Port = 587,
    EnableSsl = true,
    DeliveryMethod = SmtpDeliveryMethod.Network,
    Credentials = new NetworkCredential(fromAddress.Address, fromPassword),
    Timeout = 20000
};
using (var message = new MailMessage(fromAddress, toAddress)
{
    Subject = subject,
    Body = body
})
{
    smtp.Send(message);
}

这是我的版本：“使用 Gmail 在 C # 中发送电子邮件”。

using System;
using System.Net;
using System.Net.Mail;

namespace SendMailViaGmail
{
   class Program
   {
   static void Main(string[] args)
   {

      //Specify senders gmail address
      string SendersAddress = "[email protected]";
      //Specify The Address You want to sent Email To(can be any valid email address)
      string ReceiversAddress = "[email protected]";
      //Specify The password of gmial account u are using to sent mail(pw of [email protected])
      const string SendersPassword = "Password";
      //Write the subject of ur mail
      const string subject = "Testing";
      //Write the contents of your mail
      const string body = "Hi This Is my Mail From Gmail";

      try
      {
        //we will use Smtp client which allows us to send email using SMTP Protocol
        //i have specified the properties of SmtpClient smtp within{}
        //gmails smtp server name is smtp.gmail.com and port number is 587
        SmtpClient smtp = new SmtpClient
        {
           Host = "smtp.gmail.com",
           Port = 587,
           EnableSsl = true,
           DeliveryMethod = SmtpDeliveryMethod.Network,
           Credentials    = new NetworkCredential(SendersAddress, SendersPassword),
           Timeout = 3000
        };

        //MailMessage represents a mail message
        //it is 4 parameters(From,TO,subject,body)

        MailMessage message = new MailMessage(SendersAddress, ReceiversAddress, subject, body);
        /*WE use smtp sever we specified above to send the message(MailMessage message)*/

        smtp.Send(message);
        Console.WriteLine("Message Sent Successfully");
        Console.ReadKey();
     }

     catch (Exception ex)
     {
        Console.WriteLine(ex.Message);
        Console.ReadKey();
     }
    }
   }
 }

这是发送带有附件的电子邮件。简单而简短..

来源： http://coding-issues.blogspot.in/2012/11/sending-email-with-attachments-from-c.html

using System.Net;
using System.Net.Mail;

public void email_send()
{
    MailMessage mail = new MailMessage();
    SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
    mail.From = new MailAddress("your [email protected]");
    mail.To.Add("[email protected]");
    mail.Subject = "Test Mail - 1";
    mail.Body = "mail with attachment";

    System.Net.Mail.Attachment attachment;
    attachment = new System.Net.Mail.Attachment("c:/textfile.txt");
    mail.Attachments.Add(attachment);

    SmtpServer.Port = 587;
    SmtpServer.Credentials = new System.Net.NetworkCredential("your [email protected]", "your password");
    SmtpServer.EnableSsl = true;

    SmtpServer.Send(mail);

}

来源：在 ASP.NET C# 中发送电子邮件

下面是一个使用 C# 发送邮件的示例工作代码，在下面的示例中，我使用的是 google 的 smtp 服务器。

该代码不言自明，将电子邮件和密码替换为您的电子邮件和密码值。

public void SendEmail(string address, string subject, string message)
{
    string email = "[email protected]";
    string password = "put-your-GMAIL-password-here";

    var loginInfo = new NetworkCredential(email, password);
    var msg = new MailMessage();
    var smtpClient = new SmtpClient("smtp.gmail.com", 587);

    msg.From = new MailAddress(email);
    msg.To.Add(new MailAddress(address));
    msg.Subject = subject;
    msg.Body = message;
    msg.IsBodyHtml = true;

    smtpClient.EnableSsl = true;
    smtpClient.UseDefaultCredentials = false;
    smtpClient.Credentials = loginInfo;
    smtpClient.Send(msg);
}

更改 Gmail / Outlook.com 电子邮件的发件人：

为了防止欺骗 - Gmail/Outlook.com 不允许您从任意用户帐户名称发送邮件。

如果发件人数量有限，可以按照以下说明操作，然后将字段设置为以下地址： 从其他地址发送邮件From

如果您想从任意电子邮件地址发送（例如用户输入电子邮件的网站上的反馈表，而您不希望他们直接向您发送电子邮件），那么您能做的最好的事情就是：

        msg.ReplyToList.Add(new System.Net.Mail.MailAddress(email, friendlyName));

这样一来，您只需在电子邮件帐户中点击“回复”即可在反馈页面上回复乐队的粉丝，但他们不会收到您的实际电子邮件，这可能会导致大量垃圾邮件。

如果您在受控环境中，这很好用，但请注意，即使指定了回复，我也看到一些电子邮件客户端发送到发件人地址（我不知道是哪个）。

如果要发送后台电子邮件，请执行以下操作

 public void SendEmail(string address, string subject, string message)
 {
 Thread threadSendMails;
 threadSendMails = new Thread(delegate()
    {

      //Place your Code here 

     });
  threadSendMails.IsBackground = true;
  threadSendMails.Start();
}

并添加命名空间

using System.Threading;

下面是发送邮件并从 web.config 获取凭据的一种方法：

public static string SendEmail(string To, string Subject, string Msg, bool bodyHtml = false, bool test = false, Stream AttachmentStream = null, string AttachmentType = null, string AttachmentFileName = null)
{
    try
    {
        System.Net.Mail.MailMessage newMsg = new System.Net.Mail.MailMessage(System.Configuration.ConfigurationManager.AppSettings["mailCfg"], To, Subject, Msg);
        newMsg.BodyEncoding = System.Text.Encoding.UTF8;
        newMsg.HeadersEncoding = System.Text.Encoding.UTF8;
        newMsg.SubjectEncoding = System.Text.Encoding.UTF8;

        System.Net.Mail.SmtpClient smtpClient = new System.Net.Mail.SmtpClient();
        if (AttachmentStream != null && AttachmentType != null && AttachmentFileName != null)
        {
            System.Net.Mail.Attachment attachment = new System.Net.Mail.Attachment(AttachmentStream, AttachmentFileName);
            System.Net.Mime.ContentDisposition disposition = attachment.ContentDisposition;
            disposition.FileName = AttachmentFileName;
            disposition.DispositionType = System.Net.Mime.DispositionTypeNames.Attachment;

            newMsg.Attachments.Add(attachment);
        }
        if (test)
        {
            smtpClient.PickupDirectoryLocation = "C:\\TestEmail";
            smtpClient.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.SpecifiedPickupDirectory;
        }
        else
        {
            //smtpClient.EnableSsl = true;
        }

        newMsg.IsBodyHtml = bodyHtml;
        smtpClient.Send(newMsg);
        return SENT_OK;
    }
    catch (Exception ex)
    {

        return "Error: " + ex.Message
             + "<br/><br/>Inner Exception: "
             + ex.InnerException;
    }

}

以及 web.config 中的相应部分：

<appSettings>
    <add key="mailCfg" value="[email protected]"/>
</appSettings>
<system.net>
  <mailSettings>
    <smtp deliveryMethod="Network" from="[email protected]">
      <network defaultCredentials="false" host="mail.exapmple.com" userName="[email protected]" password="your_password" port="25"/>
    </smtp>
  </mailSettings>
</system.net>

包括这个，

using System.Net.Mail;

然后

MailMessage sendmsg = new MailMessage(SendersAddress, ReceiversAddress, subject, body); 
SmtpClient client = new SmtpClient("smtp.gmail.com");

client.Port = 587;
client.Credentials = new System.Net.NetworkCredential("[email protected]","password");
client.EnableSsl = true;

client.Send(sendmsg);

我希望这段代码能正常工作。你可以试一试。

// Include this.                
using System.Net.Mail;

string fromAddress = "[email protected]";
string mailPassword = "*****";       // Mail id password from where mail will be sent.
string messageBody = "Write the body of the message here.";


// Create smtp connection.
SmtpClient client = new SmtpClient();
client.Port = 587;//outgoing port for the mail.
client.Host = "smtp.gmail.com";
client.EnableSsl = true;
client.Timeout = 10000;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential(fromAddress, mailPassword);


// Fill the mail form.
var send_mail = new MailMessage();

send_mail.IsBodyHtml = true;
//address from where mail will be sent.
send_mail.From = new MailAddress("[email protected]");
//address to which mail will be sent.           
send_mail.To.Add(new MailAddress("[email protected]");
//subject of the mail.
send_mail.Subject = "put any subject here";

send_mail.Body = messageBody;
client.Send(send_mail);

为了让它正常工作，我必须启用我的 gmail 帐户，以便其他应用程序能够访问。这是通过“启用安全性较低的应用程序”完成的，也可以使用此链接：https://accounts.google.com/b/0/DisplayUnlockCaptcha

Google 可能会阻止某些未使用现代安全标准的应用或设备尝试登录。由于这些应用和设备更容易被入侵，因此阻止它们有助于提高帐户的安全性。

不支持最新安全标准的应用示例包括：

• 装有 iOS 6 或更低版本的 iPhone 或 iPad 上的“邮件”应用
  
• 8.1 版本之前的 Windows Phone 上的“邮件”应用
  
• 一些桌面邮件客户端，如Microsoft Outlook和Mozilla Thunderbird

因此，您必须在Google帐户中启用不太安全的登录。

登录Google帐户后，转到：

https://myaccount.google.com/lesssecureapps
或
https://www.google.com/settings/security/lesssecureapps

在 C# 中，可以使用以下代码：

using (MailMessage mail = new MailMessage())
{
    mail.From = new MailAddress("[email protected]");
    mail.To.Add("[email protected]");
    mail.Subject = "Hello World";
    mail.Body = "<h1>Hello</h1>";
    mail.IsBodyHtml = true;
    mail.Attachments.Add(new Attachment("C:\\file.zip"));

    using (SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587))
    {
        smtp.Credentials = new NetworkCredential("[email protected]", "password");
        smtp.EnableSsl = true;
        smtp.Send(mail);
    }
}

我遇到了同样的问题，但通过转到 gmail 的安全设置和允许不太安全的应用程序解决了这个问题。 Domenic & Donny 的代码有效，但前提是您启用了该设置

如果您已登录（Google），则可以点击此链接，然后将“打开”切换为“访问安全性较低的应用程序”

以这种方式使用

MailMessage sendmsg = new MailMessage(SendersAddress, ReceiversAddress, subject, body); 
SmtpClient client = new SmtpClient("smtp.gmail.com");

client.Port = Convert.ToInt32("587");
client.EnableSsl = true;
client.Credentials = new System.Net.NetworkCredential("[email protected]","MyPassWord");
client.Send(sendmsg);

别忘了这一点：

using System.Net;
using System.Net.Mail;

编辑 2022自 2022 年 5 月 30 日起，Google 将不再支持使用仅要求您使用用户名和密码登录 Google 帐号的第三方应用或设备。但是您仍然可以通过您的Gmail帐户发送电子邮件。

1. 转到 https://myaccount.google.com/security 并开启两步验证。如果需要，请通过电话确认您的帐户。
2. 点击“应用密码”，就在“两步验证”勾选下方。
3. 为邮件应用程序请求新密码。

现在只需使用此密码而不是您帐户的原始密码！

public static void SendMail2Step(string SMTPServer, int SMTP_Port, string From, string Password, string To, string Subject, string Body, string[] FileNames) {            
            var smtpClient = new SmtpClient(SMTPServer, SMTP_Port) {
                DeliveryMethod = SmtpDeliveryMethod.Network,
                UseDefaultCredentials = false,
                EnableSsl = true
            };                
            smtpClient.Credentials = new NetworkCredential(From, Password); //Use the new password, generated from google!
            var message = new System.Net.Mail.MailMessage(new System.Net.Mail.MailAddress(From, "SendMail2Step"), new System.Net.Mail.MailAddress(To, To));
            smtpClient.Send(message);
    }

像这样使用：

SendMail2Step("smtp.gmail.com", 587, "[email protected]",
          "yjkjcipfdfkytgqv",//This will be generated by google, copy it here.
          "[email protected]", "test message subject", "Test message body ...", null);

要使其他答案“从服务器”工作，请先为 gmail 帐户中安全性较低的应用打开访问权限。这将在 2022 年 5 月 30 日弃用

看起来最近谷歌改变了它的安全策略。评分最高的答案不再有效，直到您按照以下说明更改帐户设置： https://support.google.com/accounts/answer/6010255?hl=en-GB 截至 2016 年 3 月，谷歌再次更改了设置位置！

using System;
using System.Net;
using System.Net.Mail;

namespace SendMailViaGmail
{
   class Program
   {
   static void Main(string[] args)
   {

      //Specify senders gmail address
      string SendersAddress = "[email protected]";
      //Specify The Address You want to sent Email To(can be any valid email address)
      string ReceiversAddress = "[email protected]";
      //Specify The password of gmial account u are using to sent mail(pw of [email protected])
      const string SendersPassword = "Password";
      //Write the subject of ur mail
      const string subject = "Testing";
      //Write the contents of your mail
      const string body = "Hi This Is my Mail From Gmail";

      try
      {
        //we will use Smtp client which allows us to send email using SMTP Protocol
        //i have specified the properties of SmtpClient smtp within{}
        //gmails smtp server name is smtp.gmail.com and port number is 587
        SmtpClient smtp = new SmtpClient
        {
           Host = "smtp.gmail.com",
           Port = 587,
           EnableSsl = true,
           DeliveryMethod = SmtpDeliveryMethod.Network,
           Credentials = new NetworkCredential(SendersAddress, SendersPassword),
           Timeout = 3000
        };

        //MailMessage represents a mail message
        //it is 4 parameters(From,TO,subject,body)

        MailMessage message = new MailMessage(SendersAddress, ReceiversAddress, subject, body);
        /*WE use smtp sever we specified above to send the message(MailMessage message)*/

        smtp.Send(message);
        Console.WriteLine("Message Sent Successfully");
        Console.ReadKey();
     }
     catch (Exception ex)
     {
        Console.WriteLine(ex.Message);
        Console.ReadKey();
     }
}
}
}

试试这个

public static bool Send(string receiverEmail, string ReceiverName, string subject, string body)
{
        MailMessage mailMessage = new MailMessage();
        MailAddress mailAddress = new MailAddress("[email protected]", "Sender Name"); // [email protected] = input Sender Email Address 
        mailMessage.From = mailAddress;
        mailAddress = new MailAddress(receiverEmail, ReceiverName);
        mailMessage.To.Add(mailAddress);
        mailMessage.Subject = subject;
        mailMessage.Body = body;
        mailMessage.IsBodyHtml = true;

        SmtpClient mailSender = new SmtpClient("smtp.gmail.com", 587)
        {
            EnableSsl = true,
            UseDefaultCredentials = false,
            DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network,
            Credentials = new NetworkCredential("[email protected]", "pass")   // [email protected] = input sender email address  
                                                                           //pass = sender email password
        };

        try
        {
            mailSender.Send(mailMessage);
            return true;
        }
        catch (SmtpFailedRecipientException ex)
        { 
          // Write the exception to a Log file.
        }
        catch (SmtpException ex)
        { 
           // Write the exception to a Log file.
        }
        finally
        {
            mailSender = null;
            mailMessage.Dispose();
        }
        return false;
}

试试这个，

    private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            MailMessage mail = new MailMessage();
            SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");

            mail.From = new MailAddress("[email protected]");
            mail.To.Add("to_address");
            mail.Subject = "Test Mail";
            mail.Body = "This is for testing SMTP mail from GMAIL";

            SmtpServer.Port = 587;
            SmtpServer.Credentials = new System.Net.NetworkCredential("username", "password");
            SmtpServer.EnableSsl = true;

            SmtpServer.Send(mail);
            MessageBox.Show("mail Send");
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }

从另一个答案复制，上述方法有效，但 gmail 始终将“发件人”和“回复”电子邮件替换为实际发送的 gmail 帐户。然而，显然有一个解决方法：

http://karmic-development.blogspot.in/2013/10/send-email-from-aspnet-using-gmail-as.html

“3. 在”帐户“选项卡中，单击”添加您拥有的另一个电子邮件地址“链接，然后进行验证”

或者可能是这个

更新3：读者德里克·贝内特（Derek Bennett）说：“解决方案是进入您的gmail设置：帐户并”默认“您的gmail帐户以外的帐户。这将导致 gmail 使用默认帐户的电子邮件地址重写“发件人”字段。

你可以试试。它为您提供了更好和先进的发送邮件功能。你可以从中找到更多信息 这是一个例子Mailkit

    MimeMessage message = new MimeMessage();
    message.From.Add(new MailboxAddress("FromName", "[email protected]"));
    message.To.Add(new MailboxAddress("ToName", "[email protected]"));
    message.Subject = "MyEmailSubject";

    message.Body = new TextPart("plain")
    {
        Text = @"MyEmailBodyOnlyTextPart"
    };

    using (var client = new SmtpClient())
    {
        client.Connect("SERVER", 25); // 25 is port you can change accordingly

        // Note: since we don't have an OAuth2 token, disable
        // the XOAUTH2 authentication mechanism.
        client.AuthenticationMechanisms.Remove("XOAUTH2");

        // Note: only needed if the SMTP server requires authentication
        client.Authenticate("YOUR_USER_NAME", "YOUR_PASSWORD");

        client.Send(message);
        client.Disconnect(true);
    }

为避免 Gmail 出现安全问题，您应该先从 Gmail 设置中生成应用密码，即使您使用两步验证，也可以使用此密码而不是真实密码发送电子邮件。

如果您的 Google 密码不起作用，您可能需要为 Google 上的 Gmail 创建应用专用密码。https://support.google.com/accounts/answer/185833?hl=en

如果您现在尝试执行此操作，则不再支持此功能。

https://support.google.com/accounts/answer/6010255?hl=en&visit_id=637960864118404117-800836189&p=less-secure-apps&rd=1#zippy=

从 2022 年 6 月 1 日起，Google 增加了一些安全功能

Google 不再支持使用第三方应用或设备，这些应用或设备要求您仅使用您的用户名和密码登录您的 Google 帐户，或直接使用 Google 帐户的用户名和密码发送邮件。但是您仍然可以使用生成应用程序密码通过您的Gmail帐户发送电子邮件。

以下是生成新密码的步骤。

1. 转到 https://myaccount.google.com/security
2. 开启两步验证。
3. 如果需要，请通过电话确认您的帐户。
4. 点击“应用密码”，就在“两步验证”勾选下方。为邮件应用程序请求新密码。

现在，我们必须使用此密码来发送邮件，而不是您帐户的原始密码。

以下是发送邮件的示例代码

public static void SendMailFromApp(string SMTPServer, int SMTP_Port, string From, string Password, string To, string Subject, string Body) {            
            var smtpClient = new SmtpClient(SMTPServer, SMTP_Port) {
                DeliveryMethod = SmtpDeliveryMethod.Network,
                UseDefaultCredentials = false,
                EnableSsl = true
            };                
            smtpClient.Credentials = new NetworkCredential(From, Password); //Use the new password, generated from google!
            var message = new System.Net.Mail.MailMessage(new System.Net.Mail.MailAddress(From, "SendMail2Step"), new System.Net.Mail.MailAddress(To, To));
            smtpClient.Send(message);
    }

您可以调用如下方法

SendMailFromApp("smtp.gmail.com", 25, "[email protected]",
          "tyugyyj1556jhghg",//This will be generated by google, copy it here.
          "[email protected]", "New Mail Subject", "Body of mail from My App");

Google 已从我们的 Google 帐户中删除了安全性较低的应用程序设置，这意味着我们无法再使用实际的 Google 密码从 SMTP 服务器发送电子邮件。我们需要使用 Xoauth2 并授权用户，或者在启用了 2fa 的帐户上创建应用密码。

创建后，可以使用应用密码代替标准 gmail 密码。

class Program
{
    private const string To = "[email protected]";
    private const string From = "[email protected]";
    
    private const string GoogleAppPassword = "XXXXXXXX";
    
    private const string Subject = "Test email";
    private const string Body = "<h1>Hello</h1>";
    
    
    static void Main(string[] args)
    {
        Console.WriteLine("Hello World!");
        
        var smtpClient = new SmtpClient("smtp.gmail.com")
        {
            Port = 587,
            Credentials = new NetworkCredential(From , GoogleAppPassword),
            EnableSsl = true,
        };
        var mailMessage = new MailMessage
        {
            From = new MailAddress(From),
            Subject = Subject,
            Body = Body,
            IsBodyHtml = true,
        };
        mailMessage.To.Add(To);

        smtpClient.Send(mailMessage);
    }
}

SMTP用户名和密码未接受错误的快速修复

谷歌更新后，这是使用 c# 或 .net 发送电子邮件的有效方法。

using System;
using System.Net;
using System.Net.Mail;

namespace EmailApp
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            String SendMailFrom = "Sender Email";
            String SendMailTo = "Reciever Email";
            String SendMailSubject = "Email Subject";
            String SendMailBody = "Email Body";

            try
            {
                SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com",587);
                SmtpServer.DeliveryMethod = SmtpDeliveryMethod.Network;
                MailMessage email = new MailMessage();
                // START
                email.From = new MailAddress(SendMailFrom);
                email.To.Add(SendMailTo);
                email.CC.Add(SendMailFrom);
                email.Subject = SendMailSubject;
                email.Body = SendMailBody;
                //END
                SmtpServer.Timeout = 5000;
                SmtpServer.EnableSsl = true;
                SmtpServer.UseDefaultCredentials = false;
                SmtpServer.Credentials = new NetworkCredential(SendMailFrom, "Google App Password");
                SmtpServer.Send(email);

                Console.WriteLine("Email Successfully Sent");
                Console.ReadKey();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
                Console.ReadKey();
            }

        }
    }
}

若要创建应用密码，可以按照以下文章操作：https://www.techaeblogs.live/2022/06/how-to-send-email-using-gmail.html