email consulting is similiar to phone consulting, where you are helping other businesses to solve I.T. problems without moving from one's location.It is usually done over a longer period of time (example a week). It can also be combined with phone consulting and onsite consulting ( a customised package deal)
Long term, it is very economical for small business to use this method who might not need to hire someone permanently or cannot afford to hire a contractor for a few months.

The company could solve most internal I.T. problems with a good anchor support via email ready to contact at any time.
The real benefit is that the company is receiving specific solutions for that company problem - often, Internet Research (While fantastic) is very general and does not meet the needs of that company / person at that particualr time.