Ok so, I have created a sort of Email dispatch system that will go out to various users and it will be emailed to the emails provided. Now, in the email I want to have a link to the home page of my site, or any page of the site, however I want them to be logged in already. As in, I don't want the user to have to log in, it should know the credentials by the email.

I don't have enough knowledge of how Zen Cart handles username and passwords but I've seen it done before for other sites, thought it'd be a nice feature. Does Zen Cart embed the username and password into the URL? Or some way else?