C# - Export emails from Outlook PST file to RFC822 message files (*.eml)¶

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
    {
        // Export emails from Outlook folder/PST file to rfc822 message files.
        static void ExportMailItemToRfc822(Outlook.Folder folder, string destFolder)
        {
            var items = folder.Items;
            for (int i = 1; i < items.Count; i++)
            {
                var mailItem = (Outlook.MailItem)items[i];

                string tempMsgFile = string.Format("{0}\\temp_{1}.msg", destFolder, i);
                mailItem.SaveAs(tempMsgFile, Outlook.OlSaveAsType.olMSGUnicode);

                var mail = new EAGetMail.Mail("TryIt");
                mail.LoadOMSG(tempMsgFile);
                mail.Update();
                string rfc822MessageFile = string.Format("{0}\\rfc822_{1}.eml", destFolder, i);
                mail.SaveAs(rfc822MessageFile, true);

                File.Delete(tempMsgFile);
            }
        }

        static void Main(string[] args)
        {
            var app = new Outlook.Application();
            // get default inbox folder
            var folder = (Outlook.Folder)
                app.GetNamespace("MAPI").GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);

            /*
            * If you want to export emails from
            * existed PST file. You can use the following codes.
            * app.Session.AddStore("d:\\tempFolder\\source.pst");
            * var folder = app.GetNamespace("MAPI").Folders.GetLast();
            */

            ExportMailItemToRfc822(folder,
                "d:\\destFolder");

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