It seems like not answering to e-mails is one of the traits of the e-relationships. This is a source of annoyance for many people.
Since Seth Godin revolutionized the e-mail based market relationships no other developments have been significant in this field.
I claim for a Recognition Marketing as a way of completing what the Permission Marketing left incomplete. Recognition Marketing is the other side of the e-mail based relationships. This is how I explain it.
The fact is that technology enables close conversations and fluency in relationships but it also allows setting barriers or distance in conversations. I think we all have a right to stay silent but a sense of acknowledgement should foster people to answer to any e-mail. At least if there is a previous permission from the other part. I think sometimes people get obsessed with advertising techniques and traffic issues and forget the most basic traits of any kind of relationship, recognition and respect.
Permission marketing + Recognition marketing = Marketing with a human face