c# - 如何将 MailMessage 对象作为 *.eml 或 *.msg 文件保存到磁盘

Question

如何将 MailMessage 对象保存到磁盘？MailMessage 对象不公开任何 Save() 方法。

如果它以任何格式保存，*.eml 或 *.msg，我没有问题。知道怎么做吗？

Answer 1

为简单起见，我将仅引用Connect 项的解释：

您实际上可以将 SmtpClient 配置为将电子邮件发送到文件系统而不是网络。您可以使用以下代码以编程方式执行此操作：

SmtpClient client = new SmtpClient("mysmtphost");
client.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
client.PickupDirectoryLocation = @"C:\somedirectory";
client.Send(message);

您也可以在应用程序配置文件中进行设置，如下所示：

 <configuration>
     <system.net>
         <mailSettings>
             <smtp deliveryMethod="SpecifiedPickupDirectory">
                 <specifiedPickupDirectory pickupDirectoryLocation="C:\somedirectory" />
             </smtp>
         </mailSettings>
     </system.net>
 </configuration>

发送电子邮件后，您应该会看到电子邮件文件已添加到您指定的目录中。然后，您可以让一个单独的进程以批处理模式发送电子邮件。

您应该能够使用空构造函数而不是列出的构造函数，因为无论如何它都不会发送它。

Answer 2

这是将 MailMessage 转换为包含 EML 数据的流的扩展方法。显然，它使用文件系统有点破解，但它可以工作。

public static void SaveMailMessage(this MailMessage msg, string filePath)
{
    using (var fs = new FileStream(filePath, FileMode.Create))
    {
        msg.ToEMLStream(fs);
    }
}

/// <summary>
/// Converts a MailMessage to an EML file stream.
/// </summary>
/// <param name="msg"></param>
/// <returns></returns>
public static void ToEMLStream(this MailMessage msg, Stream str)
{
    using (var client = new SmtpClient())
    {
        var id = Guid.NewGuid();

        var tempFolder = Path.Combine(Path.GetTempPath(), Assembly.GetExecutingAssembly().GetName().Name);

        tempFolder = Path.Combine(tempFolder, "MailMessageToEMLTemp");

        // create a temp folder to hold just this .eml file so that we can find it easily.
        tempFolder = Path.Combine(tempFolder, id.ToString());

        if (!Directory.Exists(tempFolder))
        {
            Directory.CreateDirectory(tempFolder);
        }

        client.UseDefaultCredentials = true;
        client.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
        client.PickupDirectoryLocation = tempFolder;
        client.Send(msg);

        // tempFolder should contain 1 eml file

        var filePath = Directory.GetFiles(tempFolder).Single();

        // stream out the contents
        using (var fs = new FileStream(filePath, FileMode.Open))
        {
            fs.CopyTo(str);
        }

        if (Directory.Exists(tempFolder))
        {
            Directory.Delete(tempFolder, true);
        }
    }
}

然后，您可以获取返回的流并按照您的意愿使用它，包括保存到磁盘上的另一个位置或存储在数据库字段中，甚至作为附件发送电子邮件。

Answer 3

如果您使用的是Mailkit。只需写下面的代码

string fileName = "your filename full path";
MimeKit.MimeMessage message = CreateMyMessage ();
message.WriteTo(fileName);

Answer 4

在社区的帮助下，我想出了一个.NET 5的解决方案。我将 这个旧解决方案与这篇文章中的建议结合起来，并受到Mailkit的启发，它产生了很好的扩展方法，没有不必要的依赖

public static class MailMessageHelper
{
    public static void WriteTo(this MailMessage mail, Stream stream)
    {
        Assembly assembly = typeof(SmtpClient).Assembly;
        Type _mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");

        // Get reflection info for MailWriter contructor
        ConstructorInfo _mailWriterConstructor =
            _mailWriterType.GetConstructor(
                BindingFlags.Instance | BindingFlags.NonPublic,
                null,
                new Type[] { typeof(Stream), typeof(bool) },
                null);

        // Construct MailWriter object with our FileStream
        object _mailWriter =
          _mailWriterConstructor.Invoke(new object[] { stream, true });

        // Get reflection info for Send() method on MailMessage
        MethodInfo _sendMethod =
            typeof(MailMessage).GetMethod(
                "Send",
                BindingFlags.Instance | BindingFlags.NonPublic);

        // Call method passing in MailWriter
        _sendMethod.Invoke(
            mail,
            BindingFlags.Instance | BindingFlags.NonPublic,
            null,
            new object[] { _mailWriter, true, true },
            null);

        // Finally get reflection info for Close() method on our MailWriter
        MethodInfo _closeMethod =
            _mailWriter.GetType().GetMethod(
                "Close",
                BindingFlags.Instance | BindingFlags.NonPublic);

        // Call close method
        _closeMethod.Invoke(
            _mailWriter,
            BindingFlags.Instance | BindingFlags.NonPublic,
            null,
            Array.Empty<object>(),
            null);
    }
}

用法

MailMessage mail = new(mailFrom, mailTo, mailSubject, mailContent);
mail.WriteTo(new FileStream(@"path_to_file\new_mail.eml", FileMode.Create));

此外，如果您正在使用MemoryStream并想要获得结果string，只需更改扩展方法的返回类型并在最后写入

return Encoding.ASCII.GetString(stream.ToArray());

享受

Answer 5

由于某种原因，client.send 失败（在使用该方法实际发送之后），所以我插入了良好的 'ole CDO 和 ADODB 流。在设置 .Message 值之前，我还必须使用 template.eml 加载 CDO.message。但它有效。

由于上面的一个是 C 这里是一个用于 VB

    MyMessage.From = New Net.Mail.MailAddress(mEmailAddress)
    MyMessage.To.Add(mToAddress)
    MyMessage.Subject = mSubject
    MyMessage.Body = mBody

    Smtp.Host = "------"
    Smtp.Port = "2525"
    Smtp.Credentials = New NetworkCredential(------)

    Smtp.Send(MyMessage)        ' Actual Send

    Dim oldCDO As CDO.Message
    oldCDO = MyLoadEmlFromFile("template.eml")  ' just put from, to, subject blank. leave first line blank
    oldCDO.To = mToAddress
    oldCDO.From = mEmailAddress
    oldCDO.Subject = mSubject
    oldCDO.TextBody = mBody
    oldCDO.HTMLBody = mBody
    oldCDO.GetStream.Flush()
    oldCDO.GetStream.SaveToFile(yourPath)

Answer 6

试试这个

请使用这 2 个参考（使用 MailBee；）（使用 MailBee.Mime；）

    public static string load(string to,string from,string cc,string bcc,string subject,string body, List<string> reportList,string path, bool HtmlbodyType)
    {
        try
        {
            MailBee.Mime.MailMessage msg = new MailBee.Mime.MailMessage();
            msg.From.AsString = from;
            msg.Subject = subject;
            if (HtmlbodyType == true)
            {
                msg.BodyHtmlText = body;
            }
            else
            {
                msg.BodyPlainText = body;
            }
            
            string[] receptionEmail = to.Split(new string[] { ",", ";" }, StringSplitOptions.RemoveEmptyEntries);
            string[] ccEmail = cc.Split(new string[] { ",", ";" }, StringSplitOptions.RemoveEmptyEntries);
            string[] bccEmail = bcc.Split(new string[] { ",", ";" }, StringSplitOptions.RemoveEmptyEntries);
            string message = "";
            foreach (string To in receptionEmail)
            {
                msg.To.Add(To);
            }
            foreach (string CC in ccEmail)
            {
                    msg.Cc.Add(CC);
            }
            foreach (string Bcc in bccEmail)
            {
                    msg.Bcc.Add(Bcc);

            }
                for (int x = 0; x < reportList.Count; x++)
                {
                    string fileName = reportList[x];
                    msg.Attachments.Add(fileName);
                }

                msg.SaveMessage(path);
                return "Success";
            
        }
        catch (Exception ex)
        {
            return ex.Message;
        }

    }