[Cilvic]

Why not price it purely per email?

Let them start small, then "upsell" on more emails.

Also I guess for many users this is not an "ongoing activity" more like a one-time, let's run this campaign.

Also 100,000 /month is really a lot no, how many month could I really find that many dental clinics?

[evganin]

The subscription-based model is more convenient in terms of revenue forecasting. It very depends on the subject matter. You won't find 100,000 dentists, for example. It's possible to find around 30,000