Based on a research study done in 2011 by a financial firm that markets to modestly affluent to affluent seniors, 34% cited word of mouth as the basis of starting business with a financial firm, while 33% cited off line media as the source (mail,workshops, seminars, etc.).
What this translates to, by keeping in touch with your book of business, you can have just as great of results in marketing as you do in off line traditional marketing.
Source Entrepreneur.com
