Wanted: Large Email List, Now!

Every few months, someone asks me, "How can I build a big list quickly?" This question usually comes from an email newcomer, often an entrepreneur or small-business executive just getting his business going or a marketer who comes from the direct-mail world or another discipline. 
 
They're all looking for the "easy" button, the one best way to make a mailing list grow overnight. But, as I've written previously, there is no "easy" button for email marketing.  
 
To begin with, the rules are different for email, beginning with permission and continuing on with cadence, content and deliverability via the spam-complaint button.
 
Having a large list sounds ideal, but it guarantees nothing -- except, perhaps, potential deliverability challenges. It certainly doesn't ensure the high ROI for which email is famous...