ASP.NET C# 电子邮件附件在发送到多个电子邮件地址时最终变为 0 字节

Question

我有这个例程，可以按如下方式将电子邮件发送到列表，并且我已经对其进行了测试。我收到的第一封电子邮件没问题，但第二封电子邮件的字节数比实际文件呈现的字节数少，无法打开。我怎样才能使每个电子邮件附件都能正确发送而不发送任何 0 字节附件？我通过 ASP.NET C# webform 将附件直接发送给收件人，但大多数 PDF 附件都是由于错误消息解码不当而发送的。这是页面的主要电子邮件代码：

if (emailIsValid(EmailToSend))
{
    string TheSubject = SubjectTxt.Text;
    string TheBody = "Dear " + FirstName + ",<br/><br/>" + MessageTxt.Text;
    TheBody = TheBody + " EMail Body "
    string BodyTxt = TheBody.Replace(Environment.NewLine, "<br />");

    MailMessage mailObj = new MailMessage(
        "noreply@company.com", EmailToSend, TheSubject, BodyTxt);
    SmtpClient SMTPServer = new SmtpClient("unknown.company.com");

    string RPT = FromTxt.Text;
    mailObj.ReplyToList.Add(RPT);
    mailObj.BodyEncoding = System.Text.Encoding.UTF8;
    mailObj.IsBodyHtml = true;


    string filePath = txtAttachment.PostedFile.FileName;
    string filename = Path.GetFileName(filePath);
    string ext = Path.GetExtension(filename);
    string contenttype = String.Empty;

    //Set the contenttype based on File Extension
    switch (ext)
    {
        case ".doc":
            contenttype = "application/vnd.ms-word";
            break;
        case ".docx":
            contenttype = "application/vnd.ms-word";
            break;
        case ".xls":
            contenttype = "application/vnd.ms-excel";
            break;
        case ".xlsx":
            contenttype = "application/vnd.ms-excel";
            break;
        case ".ppt":
            contenttype = "application/vnd.ms-powerpoint";
            break;
        case ".pptx":
            contenttype = "application/vnd.ms-powerpoint";
            break;
        case ".jpg":
            contenttype = "image/jpg";
            break;
        case ".png":
            contenttype = "image/png";
            break;
        case ".gif":
            contenttype = "image/gif";
            break;
        case ".pdf":
            contenttype = "application/pdf";
            break;
        case ".csv":
            contenttype = "text/csv";
            break;
        case ".txt":
            contenttype = "text/csv";
            break;
        default:
            contenttype = "Unknown Content Type";
            break;


    }

    if (txtAttachment.PostedFile != null && contenttype != "Unknown Content Type")
    {
        try
        {
            string strFileName =
            System.IO.Path.GetFileName(txtAttachment.PostedFile.FileName);
            Attachment attachFile =
            new Attachment(txtAttachment.PostedFile.InputStream, strFileName, contenttype);                                           
            mailObj.Attachments.Add(attachFile);
        }
        catch
        {

        }
    }

    try
    {
        SMTPServer.Send(mailObj);

        SqlConnection con2 = new SqlConnection(CS);

        con2.Open();

        DateTime now = DateTime.Now;
    }
catch
    {
    }

Answer 1

之前

Attachment attachFile =
        new Attachment(txtAttachment.PostedFile.InputStream, strFileName, contenttype);

尝试重置流光标，如下所示：

txtAttachment.PostedFile.InputStream.Position = 0;
Attachment attachFile =
        new Attachment(txtAttachment.PostedFile.InputStream, strFileName, contenttype);

ASP.NET C# 电子邮件附件在发送到多个电子邮件地址时最终变为 0 字节

ASP.NET C# Email Attachments Eventually go to 0 Bytes When Sending to Multiple Email Addresses

c#

pdf

asp.net

email-attachments

c#-4.0