I have tried many email templates because email marketing for offline leads DOES work and it is both cost and time effective. I can send out 30 emails and almost always get at least one reply. Usually positive to learn more, which is all I am trying to accomplish at that point. Now the trick to being taken seriously is to do a press release about your own company (make it sound like you are THE authority in your field) and include a link in your emails. Also include a link to your linkedin profile. Make sure you have 500+ contacts and lots of activity. Lots of business people are members of linkedin and when they see 500+ they think "wow this guy means business" (well enough of them do). Try it, you will see an increase in positive emails replies and call backs from offline prospects.