No. The email subscribers are Groupon's customers - if you define "customer" as "where the money comes from".
Every day Groupon sends out a daily deal to their email subscribers. Some percent of those subscribers opt to purchase the deal and go to Groupon's website and pay with a credit card. That's where the money comes from. Groupon then distributes some of that money at a later date to the merchant offering the deal.
So their success is very much dependent on the size of their email list, because that is the maximum number of potential customers (payers). Zero subscribers means zero money. If all the merchants dropped out that subscriber list could still make money via affiliate or other partner revenue.
Every day Groupon sends out a daily deal to their email subscribers. Some percent of those subscribers opt to purchase the deal and go to Groupon's website and pay with a credit card. That's where the money comes from. Groupon then distributes some of that money at a later date to the merchant offering the deal.
So their success is very much dependent on the size of their email list, because that is the maximum number of potential customers (payers). Zero subscribers means zero money. If all the merchants dropped out that subscriber list could still make money via affiliate or other partner revenue.