We humans were meant for the human touch. We can tell so much from a person’s glance, such as if they look you in the eye or avoid that. If they look at you sideways or not at all. We can tell a lot by body language, such as if people seem to be shutting you out by crossing their arms while you are talking, or if they mimic your body posturing while you are having a conversation. We also judge people by the tone of their voice; is it welcoming, distant, condescending, or more.
How, then, do you read a person by their emails? There are the obvious points, such as their use of grammar, the politeness (or not) of their salutation and closing remarks, and use of capitals for whole words or sentences, and the use and overuse of emoticons. But that doesn't tell you the whole story by any means.
My feeling, for business, is that the initial contact via electronic means is great. It is a good time saver and helps you to weed out the obvious unsuitable candidates. It is an improvement over methods before we had the ability to find out about people via the internet. It is also easier to uncover more details about people and companies.
The end step, however, still needs that human touch. Nothing can make up for that first impression in person. You may not get a second chance to make a first impression through one form of contact, but the human touch after the electronic introduction does indeed give you that second chance.