When you access the SmarterMail (Webmail), you are actually going directly to the mail server and viewing an e-mails that your e-mail client (Program such as Outlook, Outlook Express, Thunderbird, Netscape, etc.) has not yet retrieved and downloaded from the server.
In most cases, once your mail client has retrieved your messages, they are removed from the server and therefore are no longer viewable using SmarterMail (Webmail).
If you are out of the office (at home, on vacation, etc.) and you close your e-mail client (Program such as Outlook, Outlook Express, Thunderbird, Netscape, etc. or for that matter have your whole computer off to save electricity) messages will be available for viewing within the SmarterMail (Webmail).