It does not have to be the net..
Think of the dialog process again. When did you last carry out a conversation where you spoke a sentence or a paragraph and waited for th answer for a week or two? This is what you must do when you depend on a paper mailer to communicate.
How many customers will take the trouble to write back to you in response if they had to depend on putting pen to paper?
Accept it. The net is the reality. And the reality is that every time you are sending a mailer out to hundreds of customers, you are creating opportunities to have conversations with them; not one way, not one-off. Will the conversations be in tens in number or hundreds or in thousands? How meaningful will they be? How much will they advance your communication objective? That will depend on how prepared you are with relevant, precisely targeted content that enable this whole dialogue process.
More conversations with your prospects/ customers and more meaningful ones at that. Will you sell more or less as a result?