How Does An Opt-In List Differ From An Ezine?
Opt in lists are informal and brief. They are full of tips, etc. and have limited period offers. Invariably opt in lists are mailed when something new is to be introduced or to tell its users that a particular offer is available only for the next 48 hours, or something like that. Ezines, on the other hand, are formal. These carry articles and other hints. The periodicity of Ezines can be anything from a daily to once in two weeks or once a month. Actually if you really look at it, you’ll find that both opt in lists and Ezines are quite integrated. Ezines have opt in lists built into them, in the sense that along with their usual features, they include a section where they announce a new product launch, perhaps offering it to their subscribers at a special price or as a free download in the next 24 hours.
Double Optin Lists
Double opt in is when your subscriber opts in two times. How? First on the website when he/she click and confirm their subscription after giving their email id and name. After this they click on the link sent to them at the email address which they signed up with to confirm their subscription. So it means not only opting to be on the list, but also confirming it by verifying their email ids.
Opt Out Lists
Opt out is when your subscriber asks for his/her email address to be deleted from your list when they no longer want to receive messages from you. They can do this through the “unsubscribe” link that you include in your emails to them. But did you know that some online marketers provide their users an unsubscribe link that does not work. When the user clicks the link, it sometimes goes into the wrong hands adding the user to some spammer’s list under the assumption that the email address is being validated.
These days, reputed companies make sure that they only send email to subscribers when they permit them to. By sending email to those who opted not to receive them will only end up irritating the user and mess up the credibility of the online business. Why lose all the effort you put in by simply not respecting your customer?

Another Garyshack Blog.