Despite the reach of email, asking in person is the significantly more effective approach; you need to ask six people in person to equal the power of a 200-recipient email blast. Still, most people tend to think the email ask will be more effective. In research Mahdi Roghanizad of Western University and I conducted, recently published in the Journal of Experimental Social Psychology, we have found that people tend to overestimate the power of their persuasiveness via text-based communication, and underestimate the power of their persuasiveness via face-to-face communication. - hbr.org