UserID Sent with HTTP request

Hello all - I’m trying to set up Piwik to track specific users from unique URL’s that I’ll send in email beats. For instance, I would send user ABCD an email with a link that is something like Website Hosting - Mysite.com

Is this something that Piwik can do? I’ve read over the meager “UserID” section around 100 times but I can’t find anything there or on the forum… any help would be greatly appreciated.

Thanks!