Yes and no. It all depends on how many are spam and how many are welcome emails with registration info. People register in websites and go check their confirmation links. Then forget about it.

Out of that, one percent of welcome emails means 10K real visits daily, and that is good enough for a steady ad revenue flow.

If only 10% signup, then 10% of that purchase....These are dangerous ways to make a business, though we all do them while daydreaming...