Trigger a macro after a new mail is received - vba

Question

I have a macro that prompts you to save an email to a specified folder before you send it, but I can't get the macro to work for receiving emails.
This is what I have for sending emails:
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
If TypeOf Item Is Outlook.MailItem Then
Cancel = Not SaveSentMail(Item)
End If
End Sub
Private Function SaveSentMail(Item As Outlook.MailItem) As Boolean
Dim F As Outlook.MAPIFolder
If Item.DeleteAfterSubmit = False Then
Set F = Application.Session.PickFolder
If Not F Is Nothing Then
Set Item.SaveSentMessageFolder = F
SaveSentMail = True
End If
End If
End Function

Answer 1

Work with Application.Startup Event (Outlook) and Items.ItemAdd Event (Outlook)
Items.ItemAdd Event (Outlook) Occurs when one or more items are added to the specified collection. This event does not run when a large number of items are added to the folder at once. This event is not available in Microsoft Visual Basic Scripting Edition (VBScript).
Application.Startup Event (Outlook) Occurs when Microsoft Outlook is starting, but after all add-in programs have been loaded.
Code Example
Private WithEvents Items As Outlook.Items
Private Sub Application_Startup()
Dim olNs As Outlook.NameSpace
Dim Inbox As Outlook.MAPIFolder
Set olNs = Application.GetNamespace("MAPI")
Set Inbox = olNs.GetDefaultFolder(olFolderInbox)
Set Items = Inbox.Items
End Sub
Private Sub Items_ItemAdd(ByVal Item As Object)
Dim Folder As Outlook.MAPIFolder
If TypeOf Item Is Outlook.mailitem Then
Set Folder = Application.Session.PickFolder
If Folder Is Nothing Then Exit Sub
Item.Move Folder
End If
End Sub

Answer 2

You can handle the NewMailEx event of the Application class which is fired when a new message arrives in the Inbox and before client rule processing occurs. You can use the Entry ID returned in the EntryIDCollection array to call the NameSpace.GetItemFromID method and process the item. Use this method with caution to minimize the impact on Outlook performance.
Be aware, for users with an Exchange Server account (non-Cached Exchange Mode or Cached Exchange Mode), the event will fire only for messages that arrive at the server after Outlook has started. The event will not fire for messages that are synchronized in Cached Exchange Mode immediately after Outlook starts, nor for messages that are already on the server when Outlook starts in non-Cached Exchange Mode.
Another possible option is to handle the ItemAdd event of the Items class which is fired when one or more items are added to the specified collection. Be aware, this event does not run when a large number of items are added to the folder at once (more than 16 - this is a well-known issue in OOM).
A better solution is to check for new items in the folder using the timer's event. Read more about possible solutions in the following articles:
Outlook NewMail event unleashed: the challenge (NewMail, NewMailEx, ItemAdd)
Outlook NewMail event: solution options
Outlook NewMail event and Extended MAPI: C# example
Outlook NewMail unleashed: writing a working solution (C# example)