It is highly likely that those e-mails no longer exist on the server. In most cases I've seen, the client-server system work like this: e-mail are only temporary stored on the server until you start your Outlook client. By default, Outlook deletes messages from the server after it retrieves them when configured as a POP3 client. At that point, they are gone from the server and exist only on the client. The exception to this is if you used initially 'keep e-mails on the server for X days' option of Outlook. In that case, the e-mails will stick around on the server for the amount of days specified in the setting.