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

Imports Outlook = Microsoft.Office.Interop.Outlook
Imports System.Runtime.InteropServices
Imports EAGetMail
Imports System.IO

Module Module1

    ' Export emails from Outlook folder/PST file to rfc822 message files.
    Sub ExportMailItemToRfc822(ByRef folder As Outlook.Folder, ByVal destFolder As String)
        Dim items = folder.Items
        For i As Integer = 1 To items.Count
            Dim mailItem = CType(items(i), Outlook.MailItem)

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

            Dim mail = New EAGetMail.Mail("TryIt")
            mail.LoadOMSG(tempMsgFile)
            mail.Update()

            Dim rfc822MessageFile As String = String.Format("{0}\rfc822_{1}.eml", destFolder, i)
            mail.SaveAs(rfc822MessageFile, True)

            File.Delete(tempMsgFile)
        Next
    End Sub

    ' Import rfc822 email file to Outlook Inbox folder Or PST file.
    Sub ImportSingleRfc822Message(ByVal fileName As String)

        Dim app = New Outlook.Application()
        Dim 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");
        ' Dim folder = app.GetNamespace("MAPI").Folders.GetLast()

        Dim mail = New EAGetMail.Mail("TryIt")
        Dim rfc822File As String = fileName
        mail.Load(rfc822File, False)

        Dim tempMsgFile As String = rfc822File & ".msg"
        mail.SaveAsOMSG(tempMsgFile, True, False)

        Dim item = CType(app.Session.OpenSharedItem(tempMsgFile), Outlook.MailItem)
        item.Save()
        item.Move(folder)

        item.Close(Outlook.OlInspectorClose.olDiscard)
        Marshal.ReleaseComObject(item)

        app.Quit()

        File.Delete(tempMsgFile)
    End Sub

    Sub Main()
        ' import all *.eml file in source folder to outlook inbox.
        Dim 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")
    End Sub

End Module