SenderEmailType generates Class doesn't support Automation (Error 430)

Question

The subroutine runs when a new item is added to a specified collection of items an Outlook mail folder. The sub checks whether the item is a mailitem and then checks whether the email address is from an exchange server.

The code throws an error when the .SenderEmailType property is specified.

Private Sub olItems_ItemAdd(ByVal Item As Object)
    
    Dim my_olMail As Outlook.MailItem
    Dim olAtt As Outlook.Attachment
    Dim SMTPAddress As String
    Dim olAttFilter As String
    Dim fso As Object
    
    Set fso = CreateObject("Scripting.FileSystemObject")
    
    If TypeName(Item) = "MailItem" Then
        
        Set my_olMail = Item
            
        If my_olMail.SenderEmailType = "EX" Then
            SMTPAddress = my_olMail.Sender.GetExchangeUser.PrimarySmtpAddress
        Else
            'must be SMTP address if not EX
            SMTPAddress = my_olMail.SenderEmailAddress
        End If


End Sub

The error that appears: https://learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/class-doesn-t-support-automation-error-430

Answer 1

The Sender-related are set on sent items only. So, you need to check whether the Sender property is not Nothing (null in C#) and only after that try to recognize the sender type:

Private Sub Application_ItemSend(ByVal Item As Object, ByRef Cancel As Boolean) Handles application.ItemSend

    Dim mailItem As Outlook.MailItem = DirectCast(Item, Outlook.MailItem)

    Dim sender As Outlook.AddressEntry = mailItem.Sender
    Dim senderAddress As String = ""

    If sender IsNot Nothing AndAlso
       (sender.AddressEntryUserType = Outlook.OlAddressEntryUserType.olExchangeAgentAddressEntry OrElse _
        sender.AddressEntryUserType = Outlook.OlAddressEntryUserType.olExchangeRemoteUserAddressEntry) Then
        Dim exchangeUser As Outlook.ExchangeUser = sender.GetExchangeUser()

        If exchangeUser IsNot Nothing Then
            senderAddress = exchangeUser.PrimarySmtpAddress()
        End If
    Else
        Dim recipient As Outlook.Recipient = application.Session.CreateRecipient(mailItem.SenderEmailAddress)
        If recipient IsNot Nothing Then
            Dim exchangeUser As Outlook.ExchangeUser = recipient.AddressEntry.GetExchangeUser()
            If exchangeUser IsNot Nothing Then
                senderAddress = exchangeUser.PrimarySmtpAddress()
            End If
        End If

        'check if senderAddress has been set with above code. If not try SenderEmailAddress
        If senderAddress = "" Then
            senderAddress = mailItem.SenderEmailAddress()
        End If
    End If

    MessageBox.Show(senderAddress)

End Sub

See Check if Outlook SenderEmailType is exchange and set variable for more information.