从 C# 发送带有附件的电子邮件，附件在 Thunderbird 中作为第 1.2 部分到达

Question

我有一个 C# 应用程序，它使用 SMTP 通过 Exchange 2007 服务器通过电子邮件发送 Excel 电子表格报告。这些附件对 Outlook 用户来说很好，但对于 Thunderbird 和 Blackberry 用户来说，附件已重命名为“第 1.2 部分”。

我发现这个article 描述了这个问题，但似乎没有给我一个解决方法。我无法控制 Exchange 服务器，因此无法在那里进行更改。在 C# 端有什么我可以做的吗？我曾尝试对正文使用短文件名和 HTML 编码，但都没有任何区别。

我的邮件发送代码是这样的：

public static void SendMail(string recipient, string subject, string body, string attachmentFilename)
{
    SmtpClient smtpClient = new SmtpClient();
    NetworkCredential basicCredential = new NetworkCredential(MailConst.Username, MailConst.Password);
    MailMessage message = new MailMessage();
    MailAddress fromAddress = new MailAddress(MailConst.Username);

    // setup up the host, increase the timeout to 5 minutes
    smtpClient.Host = MailConst.SmtpServer;
    smtpClient.UseDefaultCredentials = false;
    smtpClient.Credentials = basicCredential;
    smtpClient.Timeout = (60 * 5 * 1000);

    message.From = fromAddress;
    message.Subject = subject;
    message.IsBodyHtml = false;
    message.Body = body;
    message.To.Add(recipient);

    if (attachmentFilename != null)
        message.Attachments.Add(new Attachment(attachmentFilename));

    smtpClient.Send(message);
}

感谢您的帮助。

Answer 1

在您的电子邮件服务下使用此方法，它可以将任何电子邮件正文和附件附加到 Microsoft Outlook

使用 Outlook = Microsoft.Office.Interop.Outlook； // 如果您稍后将使用构建代理，请从本地或 nuget 引用 Microsoft.Office.Interop.Outlook

 try {
                    var officeType = Type.GetTypeFromProgID("Outlook.Application");
    
                    if(officeType == null) {//outlook is not installed
                        return new PdfErrorResponse {
                            ErrorMessage = "System cant start Outlook!, make sure outlook is installed on your computer."
                        };
                    } else {
                        // Outlook is installed.    
                        // Continue your work.
                        Outlook.Application objApp = new Outlook.Application();
                        Outlook.MailItem mail = null;
                        mail = (Outlook.MailItem)objApp.CreateItem(Outlook.OlItemType.olMailItem);
                        //The CreateItem method returns an object which has to be typecast to MailItem 
                        //before using it.
                        mail.Attachments.Add(attachmentFilePath,Outlook.OlAttachmentType.olEmbeddeditem,1,$"Attachment{ordernumber}");
                        //The parameters are explained below
                        mail.To = recipientEmailAddress;
                        //mail.CC = "con@def.com";//All the mail lists have to be separated by the ';'
    
                        //To send email:
                        //mail.Send();
                        //To show email window
                        await Task.Run(() => mail.Display());
                    }
    
                } catch(System.Exception) {
                    return new PdfErrorResponse {
                        ErrorMessage = "System cant start Outlook!, make sure outlook is installed on your computer."
                    };
                }

Answer 2

显式填写 ContentDisposition 字段就可以了。

if (attachmentFilename != null)
{
    Attachment attachment = new Attachment(attachmentFilename, MediaTypeNames.Application.Octet);
    ContentDisposition disposition = attachment.ContentDisposition;
    disposition.CreationDate = File.GetCreationTime(attachmentFilename);
    disposition.ModificationDate = File.GetLastWriteTime(attachmentFilename);
    disposition.ReadDate = File.GetLastAccessTime(attachmentFilename);
    disposition.FileName = Path.GetFileName(attachmentFilename);
    disposition.Size = new FileInfo(attachmentFilename).Length;
    disposition.DispositionType = DispositionTypeNames.Attachment;
    message.Attachments.Add(attachment);                
}

顺便说一句，对于 Gmail，您可能会遇到一些关于 ssl 安全甚至端口的例外情况！

smtpClient.EnableSsl = true;
smtpClient.Port = 587;

Answer 3

我为此编写了一个简短的代码，我想与您分享。

这里是主要代码：

public void Send(string from, string password, string to, string Message, string subject, string host, int port, string file)
{

  MailMessage email = new MailMessage();
  email.From = new MailAddress(from);
  email.To.Add(to);
  email.Subject = subject;
  email.Body = Message;
  SmtpClient smtp = new SmtpClient(host, port);
  smtp.UseDefaultCredentials = false;
  NetworkCredential nc = new NetworkCredential(from, password);
  smtp.Credentials = nc;
  smtp.EnableSsl = true;
  email.IsBodyHtml = true;
  email.Priority = MailPriority.Normal;
  email.BodyEncoding = Encoding.UTF8;

  if (file.Length > 0)
  {
    Attachment attachment;
    attachment = new Attachment(file);
    email.Attachments.Add(attachment);
  }

  // smtp.Send(email);
  smtp.SendCompleted += new SendCompletedEventHandler(SendCompletedCallBack);
  string userstate = "sending ...";
  smtp.SendAsync(email, userstate);
}

private static void SendCompletedCallBack(object sender,AsyncCompletedEventArgs e) {
  string result = "";
  if (e.Cancelled)
  {    
    MessageBox.Show(string.Format("{0} send canceled.", e.UserState),"Message",MessageBoxButtons.OK,MessageBoxIcon.Information);
  }
  else if (e.Error != null)
  {
    MessageBox.Show(string.Format("{0} {1}", e.UserState, e.Error), "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
  }
  else {
    MessageBox.Show("your message is sended", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
  }

}

在你的按钮中做这样的事情
你可以添加你的 jpg 或 pdf 文件等等。这只是一个例子

using (OpenFileDialog attachement = new OpenFileDialog()
{
  Filter = "Exel Client|*.png",
  ValidateNames = true
})
{
if (attachement.ShowDialog() == DialogResult.OK)
{
  Send("yourmail@gmail.com", "gmail_password", 
       "tomail@gmail.com", "just smile ", "mail with attachement",
       "smtp.gmail.com", 587, attachement.FileName);

}
}

Answer 4

我尝试了 Ranadheer Reddy（上图）提供的代码，效果很好。如果您使用的公司计算机具有受限服务器，您可能需要将 SMTP 端口更改为 25 并将您的用户名和密码留空，因为它们将由您的管理员自动填写。

最初，我尝试使用来自 nugent 包管理器的 EASendMail，却发现它是付费版本，有 30 天试用期。除非您打算购买它，否则不要浪费时间。我注意到程序使用 EASendMail 运行得更快，但对我来说，免费胜过快速。

只值我的 2 美分。

Answer 5

发送带有附件的电子邮件的简单代码。

来源：http://www.coding-issues.com/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 mail@gmail.com");
    mail.To.Add("to_mail@gmail.com");
    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 mail@gmail.com", "your password");
    SmtpServer.EnableSsl = true;

    SmtpServer.Send(mail);

}

Answer 6

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

        mail.From = new MailAddress(txtAcc.Text);
        mail.To.Add(txtToAdd.Text);
        mail.Subject = txtSub.Text;
        mail.Body = txtContent.Text;
        System.Net.Mail.Attachment attachment;
        attachment = new System.Net.Mail.Attachment(txtAttachment.Text);
        mail.Attachments.Add(attachment);

        SmtpServer.Port = 587;
        SmtpServer.Credentials = new System.Net.NetworkCredential(txtAcc.Text, txtPassword.Text);

        SmtpServer.EnableSsl = true;

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

private void button1_Click(object sender, EventArgs e)
{
    MailMessage mail = new MailMessage();
    openFileDialog1.ShowDialog();
    System.Net.Mail.Attachment attachment;
    attachment = new System.Net.Mail.Attachment(openFileDialog1.FileName);
    mail.Attachments.Add(attachment);
    txtAttachment.Text =Convert.ToString (openFileDialog1.FileName);
}

Answer 7

这是一个带有附件的简单邮件发送代码

try  
{  
    SmtpClient mailServer = new SmtpClient("smtp.gmail.com", 587);  
    mailServer.EnableSsl = true;  

    mailServer.Credentials = new System.Net.NetworkCredential("myemail@gmail.com", "mypassword");  

    string from = "myemail@gmail.com";  
    string to = "reciever@gmail.com";  
    MailMessage msg = new MailMessage(from, to);  
    msg.Subject = "Enter the subject here";  
    msg.Body = "The message goes here.";
    msg.Attachments.Add(new Attachment("D:\\myfile.txt"));
    mailServer.Send(msg);  
}  
catch (Exception ex)  
{  
    Console.WriteLine("Unable to send email. Error : " + ex);  
}

阅读更多Sending emails with attachment in C#

Answer 8

试试这个：

private void btnAtt_Click(object sender, EventArgs e) {

    openFileDialog1.ShowDialog();
    Attachment myFile = new Attachment(openFileDialog1.FileName);

    MyMsg.Attachments.Add(myFile);


}

Answer 9

完成Ranadheer的解决方案，使用Server.MapPath定位文件

System.Net.Mail.Attachment attachment;
attachment = New System.Net.Mail.Attachment(Server.MapPath("~/App_Data/hello.pdf"));
mail.Attachments.Add(attachment);