Get Inbox associated with mailbox that is not the main mailbox - vba

Question

I'm trying to get the inbox of a specific email address where there is more than one address connected to the same Outlook.
I can only succeed if I check the main mailbox (the first listed in Outlook).
dim outlApp as Object
dim outlNsp as Object
dim outlMapp as Object
dim outlsubMapp as Object
dim Mappar as Object
outlApp = CreateObject("Outlook.Application")
outlNsp = outlApp.GetNamespace("MAPI")
outlMapp = outlNsp.Folders.item(Mail_username)
Mappar = outlMapp.Folders
outlsubMapp = Mappar.item(6)
'6 is olFolderInbox enum value
outlsubMapp = outlNsp.GetDefaultFolder(6)
'6 is olFolderInbox enum value
Inbox = outlsubMapp.Name
If I change Mail_username I still get the first email inbox folder.

Answer 1

This macro lists every store to which you have access and the top level folders which will include their Inboxes. It shows how to access stores and folders that are not defaults.
I am not sure if this is a complete answer but it will get you started. Try the macro then come back with any questions.
Sub ListStoresAndTopLevelFolders()
Dim FldrCrnt As Folder
Dim InxFldrChild As Long
Dim InxStoreCrnt As Long
Dim StoreCrnt As Folder
With Application.Session
For InxStoreCrnt = 1 To .Folders.Count
Set StoreCrnt = .Folders(InxStoreCrnt)
With StoreCrnt
Debug.Print .Name
For InxFldrChild = .Folders.Count To 1 Step -1
Set FldrCrnt = .Folders(InxFldrChild)
With FldrCrnt
Debug.Print " " & .Name
End With
Next
End With
Next
End With
End Sub

Answer 2

You can use the Store.GetDefaultFolder method which returns a Folder object that represents the default folder in the store and that is of the type specified by the FolderType argument. This method is similar to the GetDefaultFolder method of the NameSpace object. The difference is that this method gets the default folder on the delivery store that is associated with the account, whereas NameSpace.GetDefaultFolder returns the default folder on the default store for the current profile.
To get all stores in the profile you need to use the Stores property of the Namespace class:
Sub EnumerateFoldersInStores()
Dim colStores As Outlook.Stores
Dim oStore As Outlook.Store
Dim oRoot As Outlook.Folder
On Error Resume Next
Set colStores = Application.Session.Stores
For Each oStore In colStores
Set oRoot = oStore.GetRootFolder
Debug.Print (oRoot.FolderPath)
EnumerateFolders oRoot
Next
End Sub
Private Sub EnumerateFolders(ByVal oFolder As Outlook.Folder)
Dim folders As Outlook.folders
Dim Folder As Outlook.Folder
Dim foldercount As Integer
On Error Resume Next
Set folders = oFolder.folders
foldercount = folders.Count
'Check if there are any folders below oFolder
If foldercount Then
For Each Folder In folders
Debug.Print (Folder.FolderPath)
EnumerateFolders Folder
Next
End If
End Sub