C# 打开带有附件的默认邮件客户端

嗨，我正在开发一个WPF应用程序（使用c#）

我需要有一个功能，用户可以发送文件（音频文件）作为附件通过电子邮件。 我尝试使用

Microsoft.Office.Interop.Outlook.Application

名称空间，但如果客户端计算机上未安装Outlook，它将打开Outlook，并且无法工作

我尝试使用

System.Net.Mail

命名空间的

SmtpClient（）

和

MailMessage（）

类，但没有打开电子邮件客户端。 它通过预定义的服务器发送邮件（可能是个问题，因为我不知道客户端的默认电子邮件域是什么。它有我需要的所有东西，并且工作正常

但是他们在那里使用了DllImport属性，并且使用此方法可能会出现许多问题（据我所知）。我不知道托管和非托管代码，因此我无法理解问题所在。是否可以按照上面链接中的示例进行操作。如果不可以，原因是什么

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您能否告知或提供有关如何解决我的问题的链接

您是否尝试过使用带有适当命令行的

System.Diagnostics.Process.Start（）

mailto:some.guy@someplace.com?subject=an email&body=see attachment&attachment="/files/audio/attachment.mp3"

&附件

开关用于指定文件名

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好的，我正在努力完成这项工作，但据称这是可以做到的。我正在阅读，稍后会与您联系。

您可以要求Windows shell打开mailto URL:

var url = "mailto:someone@somewhere.com";
Process.Start(url);

您需要

使用System.Diagnostics

您可以设置消息的各个部分，如主题和正文，如中所述

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不幸的是，mailto协议不支持附件，即使某些电子邮件客户端可能有处理附件的方法。

我们可以利用大多数电子邮件客户端都支持要加载的.EML文件格式这一事实

因此，如果我们扩展System.Net.Mail.MailMessage类，使其可以作为.EML文件保存到文件系统中。 可以使用Process.Start（文件名）使用默认邮件客户端打开生成的文件

要使其正常工作，我们必须在.EML文件中添加一行，其中包含“X-Unsent:1”。该行告诉加载.EML文件的电子邮件客户端，邮件必须以“新邮件”模式显示

使用extension方法的“addUnsentHeader”bool参数将此行添加到.EML文件中

扩展方法如下所示：

using System;
using System.IO;
using System.Net.Mail;
using System.Reflection;

namespace Fsolutions.Fbase.Common.Mail
{
    public static class MailUtility
    {
        //Extension method for MailMessage to save to a file on disk
        public static void Save(this MailMessage message, string filename, bool addUnsentHeader = true)
        {
            using (var filestream = File.Open(filename, FileMode.Create))
            {
                if (addUnsentHeader)
                {
                    var binaryWriter = new BinaryWriter(filestream);
                    //Write the Unsent header to the file so the mail client knows this mail must be presented in "New message" mode
                    binaryWriter.Write(System.Text.Encoding.UTF8.GetBytes("X-Unsent: 1" + Environment.NewLine));
                }

                var assembly = typeof(SmtpClient).Assembly;
                var mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");

                // Get reflection info for MailWriter contructor
                var mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);

                // Construct MailWriter object with our FileStream
                var mailWriter = mailWriterContructor.Invoke(new object[] { filestream });

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

                sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { mailWriter, true, true }, null);

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

                // Call close method
                closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);
            }
        }
    }
}

        var mailMessage = new MailMessage();
        mailMessage.From = new MailAddress("someone@yourdomain.com");
        mailMessage.Subject = "Your subject here";
        mailMessage.IsBodyHtml = true;
        mailMessage.Body = "<span style='font-size: 12pt; color: red;'>My HTML formatted body</span>";

        mailMessage.Attachments.Add(new Attachment("C://Myfile.pdf"));

        var filename = "C://Temp/mymessage.eml";

        //save the MailMessage to the filesystem
        mailMessage.Save(filename);

        //Open the file with the default associated application registered on the local machine
        Process.Start(filename);

使用如下扩展方法：

using System;
using System.IO;
using System.Net.Mail;
using System.Reflection;

namespace Fsolutions.Fbase.Common.Mail
{
    public static class MailUtility
    {
        //Extension method for MailMessage to save to a file on disk
        public static void Save(this MailMessage message, string filename, bool addUnsentHeader = true)
        {
            using (var filestream = File.Open(filename, FileMode.Create))
            {
                if (addUnsentHeader)
                {
                    var binaryWriter = new BinaryWriter(filestream);
                    //Write the Unsent header to the file so the mail client knows this mail must be presented in "New message" mode
                    binaryWriter.Write(System.Text.Encoding.UTF8.GetBytes("X-Unsent: 1" + Environment.NewLine));
                }

                var assembly = typeof(SmtpClient).Assembly;
                var mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");

                // Get reflection info for MailWriter contructor
                var mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);

                // Construct MailWriter object with our FileStream
                var mailWriter = mailWriterContructor.Invoke(new object[] { filestream });

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

                sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { mailWriter, true, true }, null);

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

                // Call close method
                closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);
            }
        }
    }
}

        var mailMessage = new MailMessage();
        mailMessage.From = new MailAddress("someone@yourdomain.com");
        mailMessage.Subject = "Your subject here";
        mailMessage.IsBodyHtml = true;
        mailMessage.Body = "<span style='font-size: 12pt; color: red;'>My HTML formatted body</span>";

        mailMessage.Attachments.Add(new Attachment("C://Myfile.pdf"));

        var filename = "C://Temp/mymessage.eml";

        //save the MailMessage to the filesystem
        mailMessage.Save(filename);

        //Open the file with the default associated application registered on the local machine
        Process.Start(filename);

var mailMessage=new mailMessage（）；
mailMessage.From=新邮件地址（“someone@yourdomain.com");
mailMessage.Subject=“此处的主题”；
mailMessage.IsBodyHtml=true；
mailMessage.Body=“我的HTML格式的正文”；
mailMessage.Attachments.Add（新附件（“C://Myfile.pdf”）；
var filename=“C://Temp/mymessage.eml”；
//将邮件消息保存到文件系统
mailMessage.Save（文件名）；
//打开在本地计算机上注册了默认关联应用程序的文件
Process.Start（文件名）；

我使用了以下帮助器类

class MAPI
{
    public bool AddRecipientTo(string email)
    {
        return AddRecipient(email, HowTo.MAPI_TO);
    }

    public bool AddRecipientCC(string email)
    {
        return AddRecipient(email, HowTo.MAPI_TO);
    }

    public bool AddRecipientBCC(string email)
    {
        return AddRecipient(email, HowTo.MAPI_TO);
    }

    public void AddAttachment(string strAttachmentFileName)
    {
        m_attachments.Add(strAttachmentFileName);
    }

    public int SendMailPopup(string strSubject, string strBody)
    {
        return SendMail(strSubject, strBody, MAPI_LOGON_UI | MAPI_DIALOG);
    }

    public int SendMailDirect(string strSubject, string strBody)
    {
        return SendMail(strSubject, strBody, MAPI_LOGON_UI);
    }


    [DllImport("MAPI32.DLL")]
    static extern int MAPISendMail(IntPtr sess, IntPtr hwnd,
        MapiMessage message, int flg, int rsv);

    int SendMail(string strSubject, string strBody, int how)
    {
        MapiMessage msg = new MapiMessage();
        msg.subject = strSubject;
        msg.noteText = strBody;

        msg.recips = GetRecipients(out msg.recipCount);
        msg.files = GetAttachments(out msg.fileCount);

        m_lastError = MAPISendMail(new IntPtr(0), new IntPtr(0), msg, how,
            0);
        if (m_lastError > 1)
            MessageBox.Show("MAPISendMail failed! " + GetLastError(), 
                "MAPISendMail");

        Cleanup(ref msg);
        return m_lastError;
    }

    bool AddRecipient(string email, HowTo howTo)
    {
        MapiRecipDesc recipient = new MapiRecipDesc();

        recipient.recipClass = (int)howTo;
        recipient.name = email;
        m_recipients.Add(recipient);

        return true;
    }

    IntPtr GetRecipients(out int recipCount)
    {
        recipCount = 0;
        if (m_recipients.Count == 0)
            return IntPtr.Zero;

        int size = Marshal.SizeOf(typeof(MapiRecipDesc));
        IntPtr intPtr = Marshal.AllocHGlobal(m_recipients.Count * size);

        int ptr = (int)intPtr;
        foreach (MapiRecipDesc mapiDesc in m_recipients)
        {
            Marshal.StructureToPtr(mapiDesc, (IntPtr)ptr, false);
            ptr += size;
        }

        recipCount = m_recipients.Count;
        return intPtr;
    }

    IntPtr GetAttachments(out int fileCount)
    {
        fileCount = 0;
        if (m_attachments == null)
            return IntPtr.Zero;

        if ((m_attachments.Count <= 0) || (m_attachments.Count >
            maxAttachments))
            return IntPtr.Zero;

        int size = Marshal.SizeOf(typeof(MapiFileDesc));
        IntPtr intPtr = Marshal.AllocHGlobal(m_attachments.Count * size);

        MapiFileDesc mapiFileDesc = new MapiFileDesc();
        mapiFileDesc.position = -1;
        int ptr = (int)intPtr;

        foreach (string strAttachment in m_attachments)
        {
            mapiFileDesc.name = Path.GetFileName(strAttachment);
            mapiFileDesc.path = strAttachment;
            Marshal.StructureToPtr(mapiFileDesc, (IntPtr)ptr, false);
            ptr += size;
        }

        fileCount = m_attachments.Count;
        return intPtr;
    }

    void Cleanup(ref MapiMessage msg)
    {
        int size = Marshal.SizeOf(typeof(MapiRecipDesc));
        int ptr = 0;

        if (msg.recips != IntPtr.Zero)
        {
            ptr = (int)msg.recips;
            for (int i = 0; i < msg.recipCount; i++)
            {
                Marshal.DestroyStructure((IntPtr)ptr,
                    typeof(MapiRecipDesc));
                ptr += size;
            }
            Marshal.FreeHGlobal(msg.recips);
        }

        if (msg.files != IntPtr.Zero)
        {
            size = Marshal.SizeOf(typeof(MapiFileDesc));

            ptr = (int)msg.files;
            for (int i = 0; i < msg.fileCount; i++)
            {
                Marshal.DestroyStructure((IntPtr)ptr,
                    typeof(MapiFileDesc));
                ptr += size;
            }
            Marshal.FreeHGlobal(msg.files);
        }

        m_recipients.Clear();
        m_attachments.Clear();
        m_lastError = 0;
    }

    public string GetLastError()
    {
        if (m_lastError <= 26)
            return errors[m_lastError];
        return "MAPI error [" + m_lastError.ToString() + "]";
    }

    readonly string[] errors = new string[] {
    "OK [0]", "User abort [1]", "General MAPI failure [2]",
            "MAPI login failure [3]", "Disk full [4]",
            "Insufficient memory [5]", "Access denied [6]",
            "-unknown- [7]", "Too many sessions [8]",
            "Too many files were specified [9]",
            "Too many recipients were specified [10]",
            "A specified attachment was not found [11]",
    "Attachment open failure [12]",
            "Attachment write failure [13]", "Unknown recipient [14]",
            "Bad recipient type [15]", "No messages [16]",
            "Invalid message [17]", "Text too large [18]",
            "Invalid session [19]", "Type not supported [20]",
            "A recipient was specified ambiguously [21]",
            "Message in use [22]", "Network failure [23]",
    "Invalid edit fields [24]", "Invalid recipients [25]",
            "Not supported [26]"
    };


    List<MapiRecipDesc> m_recipients = new
        List<MapiRecipDesc>();
    List<string> m_attachments = new List<string>();
    int m_lastError = 0;

    const int MAPI_LOGON_UI = 0x00000001;
    const int MAPI_DIALOG = 0x00000008;
    const int maxAttachments = 20;

    enum HowTo { MAPI_ORIG = 0, MAPI_TO, MAPI_CC, MAPI_BCC };
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiMessage
{
    public int reserved;
    public string subject;
    public string noteText;
    public string messageType;
    public string dateReceived;
    public string conversationID;
    public int flags;
    public IntPtr originator;
    public int recipCount;
    public IntPtr recips;
    public int fileCount;
    public IntPtr files;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiFileDesc
{
    public int reserved;
    public int flags;
    public int position;
    public string path;
    public string name;
    public IntPtr type;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiRecipDesc
{
    public int reserved;
    public int recipClass;
    public string name;
    public string address;
    public int eIDSize;
    public IntPtr entryID;
}

---

---

参考：

我无法让我的电子邮件客户端处理

附件

，正如我指出的，RFC 6068没有定义任何附件支持。我忘了提到这一点。我也尝试过使用mailto…方法，但它所做的是在我的浏览器中打开一个新选项卡。当从朋友计算机尝试它时r Outlook正在打开，但没有附件。@Raj123在将来，删除您已经尝试过的明显答案将是一个巨大的优势：D@Gudsor我尝试了mailto方法，但我觉得这种方法不可能实现附件。我尝试了您建议的方法，但正如我在浏览器中打开新选项卡之前所说的那样（我不知道mailto和我的浏览器之间有什么关系）。我正在浏览您提供的链接，但我认为我的计算机可能有一些故障，因为其他系统正在打开其默认邮件客户端。这不起作用，它会在以下行引发异常：sendMethod.Invoke（message，BindingFlags.Instance |……。我得到了与@Marjan相同的错误-但我尝试将其实现为一个“块”（而不是扩展

System.Net.Mail.MailMessage

）。此解决方案的正确实现是什么？@derekantrican当您知道发件人地址时，此方法有效。必须在mailMessage.Save之前设置发件人。因此，使用此方法时，我们似乎应该首先从默认电子邮件客户端获取帐户。Windows 10 mail似乎不使用X-Unsent标头，只需执行以下操作将其设置为非传出电子邮件.eml文件不可编辑。如何使其可编辑？这种方式在我的环境中不起作用（W7，VS2013，从测试中执行）：无错误（代码=0），没有打开的Outlook此处存在相同的问题，此代码不起作用。Win 10，VS2010，没有错误，没有打开任何内容。我们正在使用MAPI进行生产，我一点也不建议使用MAPI。它会导致HTML邮件出现问题，如果某个内容与实际不符，通常会抛出错误，使您搜索注册表修复程序，但这些修复程序很少起作用。我们正在尝试使用电子邮件现在是ML方法。CC和BCC似乎做了同样的事情。不幸的是，OP专门询问了附件。这不是OP的完美答案。但它做到了我所需要的。：）它只是在Chrome浏览器中打开一个空白页。如果有人在asp.net中需要它：重复：