I have done all the basic SEO stuff for my site like lots good content, keyword research, link building and so on, which have produced, improved results. Recently I have looked in to email marketing. Companies who sell email marketing all say the offer opt in traffic but do not say were it comes from/. Where and how do they get people to opt in to my emails and is this a cost effective method.
The Opt-in list can be build using various ways. Some websites, I am sure you have seen, have those boxes asking you to join their newsletter. Opt-in list also can be built from websites where you have to register (such as forums). There is usually a checkbox (which is most of the times checked by default ) that says that you agree to receive their newsletters.
Don't do it! You will only damage your reputation... plus it will still end up in most people's spam folder!
Just ask your visitors to register at your home page. If your content is good, they will do it gladly
You can post a "subscribe to newsletter" on just every page of your site. Also, include the solicitation in your email sig.