打开默认邮件客户端以及附件

Question

嗨，我正在使用WPF应用程序（使用c＃）。

我需要有一个功能，用户可以通过电子邮件将文件（音频文件）作为附件发送。 我尝试使用Microsoft.Office.Interop.Outlook.Application命名空间但它打开outlook并且如果客户端的计算机上没有安装outlook，则无法工作。

我尝试使用System.Net.Mail命名空间的SmtpClient()和MailMessage()类，但它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（可能是一个问题，因为我不知道我的客户端的默认电子邮件域是什么。这个链接有我需要的所有东西，它的工作正常。

但是在那里他们使用了DllImport属性，并且使用这种方法可能会产生很多问题（从我能理解的）。 我不知道托管和非托管代码，所以我无法理解问题是什么。 可以按照上面的链接中的示例进行操作。 如果不是为什么？

你能说出或提供如何处理我的问题的链接

Answer 1

我们可以利用大多数电子邮件客户端支持要加载的.EML文件格式这一事实。

因此，如果我们以一种可以将其作为.EML文件保存到文件系统的方式扩展System.Net.Mail.MailMessage类。 可以使用Process.Start（filename）使用默认邮件客户端打开生成的文件

为了使其正常工作，我们必须在.EML文件中添加一行包含“X-Unsent：1”的行。 此行告诉电子邮件客户端加载.EML文件，消息必须以“新消息”模式显示。

使用扩展方法的“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);
            }
        }
    }
}

使用这样的扩展方法：

        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);

Answer 2

您是否尝试过使用具有适当命令行的System.Diagnostics.Process.Start() ？

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

&attachment开关允许您指定文件名。

好吧，我正在努力工作，但据称可以做到。 我正在阅读这个怪物，并会回复你。

Answer 3

您可以要求Windows shell打开mailto URL：

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

您需要using System.Diagnostics 。

您可以按照RFC 6068中的描述设置消息的各个部分，如主题和正文

var url = "mailto:someone@somewhere.com?subject=Test&body=Hello";

不幸的是，即使某些电子邮件客户端可能有办法处理它，mailto协议也不支持附件。

Answer 4

我使用了以下助手类。

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;
}

使用MAPI类如下所示。

MAPI mapi = new MAPI();

mapi.AddAttachment("c:\\temp\\file1.txt");
mapi.AddAttachment("c:\\temp\\file2.txt");
mapi.AddRecipientTo("person1@somewhere.com");
mapi.AddRecipientTo("person2@somewhere.com");
mapi.SendMailPopup("testing", "body text");

// Or if you want try and do a direct send without displaying the 
// mail dialog mapi.SendMailDirect("testing", "body text");

参考： 代码项目