I am facing the following problem from 2 days.

i configured my Moss site as Forms Based Authentication.

Some of my clients are not like to enter username and password [they
don't like login page].
so for them, what i did is, i am sending a mail, mail has a link
contains user name and password as querystring parameters,

so, in my login page i retrieveing them and trying to authenticate
them.

but it's not possible in moss.
because in sharepoint,
all the credentials are stored in Sql server.

i tested in .net application,
in web.config file, i added users and authentication mode to Forms.
it's working fine with the method FormsAuthentication.Authenticate
(UserName, Password);

please help me how can i authenticate them,

if i directly connect to database and check for username and
password, the password is in encrypted format.
so that's not the way i think.