[Weblogic Portal 10 R3] URL to redirect the user to a specific page

hi,
we have the following needs:
the user may subscribe to information (news) he wishes to be notified by mail when that information is available.
The URL of the page is included in the mail he receives.

When he clicks on that URL, it should point directly to the page in the portail that contains the porlet with the info.

How do you create that URL ? Is there a class in the API that deals with that ? the GenericURL class ?
http://edocs.bea.com/wlp/docs81/javadoc/com/bea/portlet/GenericURL.html

Also, there are 2 cases:
1) the user is already connected to the portal
2) the user has not yet connected to the portal.

Is it possible to transmit the login and password in that URL, so that the connection is transparent for the user ?

Thanks for helping.