Asp.Net 电子邮件附件在移动设备 (iPhone) 上显示内联

Question

我有一个 .Net 4.5 应用程序，它发送带有附件的电子邮件。当电子邮件在桌面上打开时，它按预期工作，但在移动设备（本例中为 iPhone）上打开时，附件显示为内联 HTML 而不是附件。

但是，当我将同一封电子邮件从我的桌面转发到手机时，附件会正确显示在我的手机上，所以我几乎可以肯定它与我如何指定 mime 或内容类型、处置等有关。但是我看不出我做错了什么。

这是代码 - 请注意

att.ContentType = new System.Net.Mime.ContentType("multipart/mixed");

确实在 iPhone 上创建了一个附件，但它的类型 = mime-attachment 不会打开。

我很困惑，客户正在等待 - 非常感谢任何帮助！

private void SendNotice(string body, string attachment, string email, bool pdf = false)
    {
        MailMessage message = new MailMessage();
        message.From = new MailAddress(ConfigurationManager.AppSettings["SMTP.SendFrom"]);
        message.Subject = ConfigurationManager.AppSettings["MatchedNoticeSubject"];
        message.To.Add(new MailAddress(email));
        message.ReplyToList.Add(new MailAddress(ConfigurationManager.AppSettings["SMTP.ReplyTo"]));
        message.Body = body;
        message.IsBodyHtml = true;

        Attachment att = Attachment.CreateAttachmentFromString(attachment, "SeniorInfo.html", System.Text.Encoding.ASCII, "text/html");

        //specifying this creates an attachment of type "mime-attachment" that does not open
        //att.ContentType = new System.Net.Mime.ContentType("multipart/mixed");

        message.Attachments.Add(att);
        SmtpClient server = new SmtpClient()
        {
            EnableSsl = (ConfigurationManager.AppSettings["SMTP.EnableSSL"].ToLower() == "true"),
            Host = ConfigurationManager.AppSettings["SMTP.Server"],
            Port = Convert.ToInt16(ConfigurationManager.AppSettings["SMTP.Port"]),
            Credentials = new System.Net.NetworkCredential(ConfigurationManager.AppSettings["SMTP.Account"], ConfigurationManager.AppSettings["SMTP.Password"])
        };
        server.Send(message);
    }

Answer 1

经过反复试验后得到解决。

与直觉相反，附件 ContentDisposition 对象是只读的，这使我相信我无法干预它，但是读取的对象显然是对实际 Attachment.ContentDisposition 的引用，因为在读取实例上设置值确实（显然）纠正问题。还使用了 MediaTypeNames 的枚举 (System.Net.Mime.MediaTypeNames.Text.Html)，但我认为这不是问题。

电子邮件发送现在看起来像这样：

private void SendMatchNotice(string body, string attachment, string email, bool pdf = false)
    {
        MailMessage message = new MailMessage();
        message.From = new MailAddress(ConfigurationManager.AppSettings["SMTP.SendFrom"]);
        message.Subject = ConfigurationManager.AppSettings["MatchedNoticeSubject"];
        message.To.Add(new MailAddress(email));
        message.ReplyToList.Add(new MailAddress(ConfigurationManager.AppSettings["SMTP.ReplyTo"]));
        message.Body = body;
        message.IsBodyHtml = true;
        // Create  the file attachment for this e-mail message.
        Attachment att = Attachment.CreateAttachmentFromString(attachment, "SeniorInfo.html", System.Text.Encoding.ASCII, System.Net.Mime.MediaTypeNames.Text.Html);
        System.Net.Mime.ContentDisposition disposition = att.ContentDisposition;
        disposition.DispositionType = "attachment";
        disposition.Inline = false;
        disposition.FileName = "SeniorInfo.html";
        disposition.CreationDate = DateTime.Now;
        disposition.ModificationDate = DateTime.Now;
        disposition.ReadDate = DateTime.Now;
        message.Attachments.Add(att);
        SmtpClient server = new SmtpClient()
        {
            EnableSsl = (ConfigurationManager.AppSettings["SMTP.EnableSSL"].ToLower() == "true"),
            Host = ConfigurationManager.AppSettings["SMTP.Server"],
            Port = Convert.ToInt16(ConfigurationManager.AppSettings["SMTP.Port"]),
            Credentials = new System.Net.NetworkCredential(ConfigurationManager.AppSettings["SMTP.Account"], ConfigurationManager.AppSettings["SMTP.Password"])
        };
        server.Send(message);
    }