C# - Import RFC822 message (*.eml) emails to Outlook INBOX/PST file¶

using System;
using System.Collections.Generic;
using System.Text;
using Outlook = Microsoft.Office.Interop.Outlook;
using System.Runtime.InteropServices;
using EAGetMail;
using System.IO;

namespace PstTest
{
    class Program
    {
        // Import rfc822 email file to Outlook Inbox folder or PST file.
        static void ImportSingleRfc822Message(string fileName)
        {
            var app = new Outlook.Application();
            // get default outlook inbox
            var folder = app.GetNamespace("MAPI").
                GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);

            /*
            * If you want to create a new PST file
            * or existed PST file to store the imported
            * message, you can use the following codes.
            * app.Session.AddStore("d:\\tempFolder\\test.pst");
            * var folder = app.GetNamespace("MAPI").Folders.GetLast();
            */
            var mail = new EAGetMail.Mail("TryIt");
            string rfc822File = fileName;
            mail.Load(rfc822File, false);

            string tempMsgFile = rfc822File + ".msg";
            mail.SaveAsOMSG(tempMsgFile, true, false);

            var item = (Outlook.MailItem)app.Session.OpenSharedItem(tempMsgFile);
            item.Save();
            item.Move(folder);

            (item as Outlook._MailItem).Close(Outlook.OlInspectorClose.olDiscard);
            Marshal.ReleaseComObject(item);
            (app as Outlook._Application).Quit();

            File.Delete(tempMsgFile);
        }

        // Import rfc822 email files to Outlook Inbox folder or PST file.
        static void ImportRfc822Message(string[] files)
        {
            var app = new Outlook.Application();
            // get default outlook inbox
            var folder = app.GetNamespace("MAPI").
                GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);

            /*
            * If you want to create a new PST file
            * or existed PST file to store the imported
            * message, you can use the following codes.
            * app.Session.AddStore("d:\\tempFolder\\test.pst");
            * var folder = app.GetNamespace("MAPI").Folders.GetLast();
            */
            for (int i = 0; i < files.Length; i++)
            {
                var mail = new EAGetMail.Mail("TryIt");
                string rfc822File = files[i];
                mail.Load(rfc822File, false);

                string tempMsgFile = rfc822File + ".msg";
                mail.SaveAsOMSG(tempMsgFile, true, false);

                var item = (Outlook.MailItem)app.Session.OpenSharedItem(tempMsgFile);
                item.Save();
                item.Move(folder);
                (item as Outlook._MailItem).Close(Outlook.OlInspectorClose.olDiscard);
                Marshal.ReleaseComObject(item);

                File.Delete(tempMsgFile);
            }

            (app as Outlook._Application).Quit();
        }

        static void Main(string[] args)
        {
            // import all *.eml file in source folder to outlook inbox.
            string[] files = Directory.GetFiles("d:\\sourcefolder", "*.eml");
            ImportRfc822Message(files);

            // You can use the following code to import a single rfc822 message file.
            // ImportSingleRfc822Message("d:\\sourcefolder\\test.eml");
        }
    }
}