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

Posted 2023-02-16

【中文标题】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

【英文标题】：Sending email with attachments from C#, attachments arrive as Part 1.2 in Thunderbird

【发布时间】：2011-02-19 00:52:33

【问题描述】：

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。

【问题讨论】：

您是否尝试定义/更改Attachment.Name 属性？

不，我没有 - “获取或设置 MIME 内容类型名称值”，您对尝试什么值有什么建议吗？谢谢。

当收到带有附件的电子邮件时，Name 显示为附件的名称。所以你可以尝试任何值。

【参考方案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,$"Attachmentordernumber");
                        //The parameters are explained below
                        mail.To = recipientEmailAddress;
                        //mail.CC = "[e-mail]";//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."
                    ;
                

【参考方案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;

【讨论】：

为什么不使用FileInfo 对象来获取CreationTime、LastWriteTime 和LastAccessTime 属性？无论如何，您正在创建一个以获取 Length 属性。

不要忘记 attachment.Dispose() 否则此文件将保持锁定状态，您将无法在其上写入数据。

【参考方案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("[e-mail]", "gmail_password", 
       "[e-mail]", "just smile ", "mail with attachement",
       "smtp.gmail.com", 587, attachement.FileName);

【参考方案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。

【参考方案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 [e-mail]");
    mail.To.Add("[e-mail]");
    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 [e-mail]", "your password");
    SmtpServer.EnableSsl = true;

    SmtpServer.Send(mail);

【讨论】：

你应该用 using 语句包装 MailMessage 和 SmtpClient 以确保它们被正确处理

@Andrew - 我该怎么做？

我试过这段代码，我得到了这篇文章中显示的错误 - ***.com/questions/20845469/…

@Steam 你可以这样做using(SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com")) //code goes here using(MailMessage mail = new MailMessage()) //code goes here

【参考方案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);

【参考方案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("[e-mail]", "mypassword");  

    string from = "[e-mail]";  
    string to = "[e-mail]";  
    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#

【参考方案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);

【参考方案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);

【讨论】：

Server.MapPath 来自哪里，应该在什么时候使用？

写这本书的人可能是 ASP.NET 程序员，我认为从相对文件名中给出完整的限定文件名会有所帮助。最初的问题没有提到 ASP.NET；您可以在此处放置对文件名的完整引用。