Since For Each loops through the existing objects, if you remove these objects as you loop, you end up skipping objects. Like the ol' "release all open forms" problem.

I'd do the bold stuff below instead.

loapp=CREATEOBJ('Outlook.Application')
loSpace=loapp.getnamespace('MAPI')
mmailbox="Mailbox - "+ALLT(GETE('name')) &&the way that we access specific users accounts
loInbox=loSpace.GetDefaultFolder(6)
mdelete=MESSAGEBOX("Do you want to delete the messages in the Inbox?",292)
DO CASE
     CASE mdelete=6
          *!*     FOR EACH item in loInbox.items
          *!*          item.delete()
          *!*     ENDFOR
          Do While loInbox.Items.Count>0
               loInbox.Items(1).Delete()
          EndDo
     CASE mdelete=7
ENDCASE