Webmail downloads them as well. Although they may not be physically stored as they would be when using an email client the main thing she needs to do is get them from the server.

By using webmail the server will presume the mail has been downloaded and therefore the next time she fires up outlook it should only look for new mail.

Another option she could use webmail for is to delete any mail she doesn't need to keep. By doing that she will reduce the backlog and then the chances are outlook will not time out because there are less to download.

The bottom line is she needs to dramatically reduce the mail volume before using outlook again.