“E-mail drip marketing is a form of e-mail marketing where a company sends (“drips”) e-mail messages to subscribers on a scheduled basis established using e-mail marketing software.” (Wikipedia).

I found nice article  there which approached me more to the subject on why, how and when I should use drip marketing.

George Seybold is explaining also how to get in drip marketing.

As for me I will probably follow my industry and sector roadmaps which shows how to organize all the communication with your subscribers, prospects or customers. Roadmaps are the combination of different iMarketing techniques to use depending on the stage of your market and marketing activity.