c# - 从虚拟主机发送电子邮件而无需使用用户名和密码

Question

我写了一个 C# 程序来发送电子邮件，效果很好。此外，我还有一个用于发送电子邮件的 PHP 脚本，效果也很好。

但我的问题是:是否可以像在 PHP 中那样使用 C# 发送电子邮件，而无需指定凭据、服务器、端口等。

我想使用 C# 而不是 PHP，因为我正在创建一个 ASP.Net 网络应用程序。

这是我当前的 C# 代码:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

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

namespace $rootnamespace$
{
public partial class $safeitemname$ : Form
{
    public $safeitemname$()
    {
        InitializeComponent();
    }

    private void AttachB_Click(object sender, EventArgs e)
    {
        if (AttachDia.ShowDialog() == DialogResult.OK)
        {
            string AttachF1 = AttachDia.FileName.ToString();
            AttachTB.Text = AttachF1;
            AttachPB.Visible = true;
            AttachIIB.Visible = true;
            AttachB.Visible = false;
        }
    }

    private void AttachIIB_Click(object sender, EventArgs e)
    {
        if (AttachDia.ShowDialog() == DialogResult.OK)
        {
            string AttachF1 = AttachDia.FileName.ToString();
            AttachIITB.Text = AttachF1;
            AttachPB.Visible = true;

        }
    }





    private void SendB_Click(object sender, EventArgs e)
    {
        try
        {
            SmtpClient client = new SmtpClient(EmailSmtpAdresTB.Text);
            client.EnableSsl = true;
            client.Timeout = 20000;
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            client.UseDefaultCredentials = false;
            client.Credentials = new NetworkCredential(EmailUserNameTB.Text, EmailUserPasswordTB.Text);
            MailMessage Msg = new MailMessage();
            Msg.To.Add(SendToTB.Text);
            Msg.From = new MailAddress(SendFromTB.Text);
            Msg.Subject = SubjectTB.Text;
            Msg.Body = EmailTB.Text;

            /// Add Attachments to mail or Not
            if (AttachTB.Text == "")
            {
                if (EmailSmtpPortTB.Text != null)
                    client.Port = System.Convert.ToInt32(EmailSmtpPortTB.Text);

                client.Send(Msg);
                MessageBox.Show("Successfuly Send Message !");
            }
            else 
            {
                Msg.Attachments.Add(new Attachment(AttachTB.Text));
                Msg.Attachments.Add(new Attachment(AttachIITB.Text));
                if (EmailSmtpPortTB.Text != null)
                client.Port = System.Convert.ToInt32(EmailSmtpPortTB.Text);

                client.Send(Msg);
                MessageBox.Show("Successfuly Send Message !");
            }


        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    private void settingsBindingNavigatorSaveItem_Click(object sender, EventArgs e)
    {
        this.Validate();
        this.settingsBindingSource.EndEdit();
        this.tableAdapterManager.UpdateAll(this.awDushiHomesDBDataSet);

    }

    private void awDushiHomesEmail_Load(object sender, EventArgs e)
    {
        // TODO: This line of code loads data into the 'awDushiHomesDBDataSet.Settings' table. You can move, or remove it, as needed.
        this.settingsTableAdapter.Fill(this.awDushiHomesDBDataSet.Settings);

    }
  }
}

这是在 PHP 中的实现方式:

<?php
//define the receiver of the email
$to = 'test@hotmail.com';

//define the subject of the email
$subject = 'Test email with attachment';

//create a boundary string. It must be unique
//so we use the MD5 algorithm to generate a random hash
$random_hash = md5(date('r', time()));

//define the headers we want passed. Note that they are separated with \r\n
$headers = "From: webmaster@example.com\r\nReply-To: webmaster@example.com";

//add boundary string and mime type specification
$headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-".$random_hash."\"";

//read the atachment file contents into a string,
//encode it with MIME base64,
//and split it into smaller chunks
$attachment = chunk_split(base64_encode(file_get_contents('PDFs\Doc1.pdf')));

//define the body of the message.
ob_start(); //Turn on output buffering
?>

--PHP-mixed-<?php echo $random_hash; ?> 
Content-Type: multipart/alternative; boundary="PHP-alt-<?php echo $random_hash; ?>"

--PHP-alt-<?php echo $random_hash; ?> 
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Hello World!!!
This is simple text email message.

--PHP-alt-<?php echo $random_hash; ?> 
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

<h2>Hello World!</h2>
<p>This is something with <b>HTML</b> formatting.</p>

--PHP-alt-<?php echo $random_hash; ?>--

--PHP-mixed-<?php echo $random_hash; ?> 
Content-Type: application/zip; name="Doc1.pdf" 
Content-Transfer-Encoding: base64 
Content-Disposition: attachment 

<?php echo $attachment; ?>
--PHP-mixed-<?php echo $random_hash; ?>--

<?php
//copy current buffer contents into $message variable and delete current output buffer
$message = ob_get_clean();

//send the email
$mail_sent = @mail( $to, $subject, $message, $headers );
//if the message is sent successfully print "Mail sent". Otherwise print "Mail failed"
echo $mail_sent ? "Mail sent" : "Mail failed";
?> 

我不是要你写我的代码，但也许你可以提供一些信息或让我知道是否可能。

编辑:

我的问题不是不使用 smtp 服务器，而是如何发送电子邮件而无需输入用户名和密码。我知道，只有当发送电子邮件的请求来 self 的服务器时，它才会起作用。

Answer 1

在 PHP 中您可以在不指定 SMTP 凭据的情况下发送邮件的原因是因为其他人已经为您配置了 php.ini 或 sendmail.ini(php 解释器用来获取某些值的文件)。

这通常是托管主机的情况(或者如果您在开发电脑上使用 php 和 AMPPS 等工具，它可以让您通过 UI 轻松编辑 SMTP 设置并忘记它)。

在 ASP.net/c# 中有 app.config 或 web.config 文件，您可以在其中注入(inject) smtp 设置(在 <mailSettings> 标记中)和因此实现与 PHP 相同的结果(SmtpClient 将自动使用存储在那里的凭据)。

查看这些问题的示例:

SmtpClient and app.config system.net configuration

SMTP Authentication with config file's MailSettings