If you only want to search through unread messages, select Unread from the Show drop-down menu. The Filter feature enables you to specify very narrow search parameters which work in conjunction with the comparison and value features described below. Filter also takes into account the preferences selected under Mailbox and Show . The comparison selector allows you to determine how the filter is to be applied to each selection. The comparison is made between the value typed into the text-box below and each piece of mail.
Value refers to the text typed into the text-box below.
All comparisons are made to the part of the message specified by the Filter selection above.