The delete() method moves the item to the Trash folder.

Use the method ItemsCollection.remove(int index) to remove the item from the folder without moving it to the Trash.

To check if an item is deleted, have to find out if it's stored in the Deleted Items folder:

    private static boolean isDeleted(Outlook outlook, OutlookItem item)
    {
        OutlookFolderID trashFolderId =
                outlook.getDefaultFolder(FolderType.DELETED_ITEMS).getFolderId();

        OutlookFolder parentFolder = item.getParentFolder();

        while(parentFolder != null)
        {
            if(parentFolder.getFolderId().equals(trashFolderId))
            {
                return true;
            }
            
            parentFolder = parentFolder.getParentFolder();
        }
        
        return false;
    }