See http://wp.netscape.com/eng/mozilla/ns7/relnotes/7.html.

>Bill,
>
>I think the option Sergey is referring to is no longer in Netscape/Mozilla. Is Netscape set as the default mail application? "Edit | Preferences | Mail & Newsgroups" first tab.
>
>>Hi Sergey
>>He's running Netscape 7.02 with Mozilla 1.0.2. You're probably running Mozilla 1.3, right? Maybe Netscape hasn't caught up with this MAPI option.
>>Bill Wright