COUNTD(IF [Visits to Walk-Through/Trial]>0 THEN [Contact E-Mail] END)
Note I made an edit to my original calculation and you will need to use an Extract for COUNTD to be available (assume you know this since you already mentioned using COUNTD previously)
I'm not sure what you mean by I need to use an Extract for COUNTD.
But your formula is working!
Thank you for your help!
Great, I'm glad to help!
If you connect to an Excel spreadsheet (or text file or Access DB) as a "live" connection, COUNTD is not an available aggregation. So, you are working with extracted data. If you are interested, there's some more info here: Accessing Count Distinct (COUNTD) | Tableau Software