title: Google Analytics - Custom Variable combine with User ID
body: <p>I want to send out newsletters which are linking to my website. On my website, all content except the landing page from the NL is protected by authentication login.</p>
  
  <p>I want to build a detailed customer journey for all recipients and all logged in website users.</p>
  
  <p>I think I will need the following two things:
  1. <strong>Custom Variable</strong> for the NL with an individual ID
  2. <strong>User ID</strong> for the authentication login</p>
  
  <p>Am I right? AND, the most important thing, how can I <strong>combine</strong> this two values correctly?</p>
  
  <p>Please note: I don't want to analyze personal information as it's not allowed in GA. But what I want to do is that the data from GA is exported via the GA API to Tableau to make reports for every user. Do you think I could make this in that way?</p>