Not every email marketing campaign has to be based around a newsletter. In fact, you have quite a few different options for connecting with your subscribers and they don´t even have to be regular . . . unless that´s what you prefer, of course.
Email Marketing Alternatives
Ezines: These are slightly different from a newsletter in that ezines tend to be longer and have more information, rather than news. They are most often available in HTML format, though you can also offer text. Sent out on a regular basis, weekly or monthly.
Updates: Let subscribers know about the latest changes to your website. These are sent out as needed, not usually more than once a month.
Special offers: This is another email marketing option. Special offers can be anything from freebies you offer to coupons for a third party business. Send these out whenever you want, no schedule is required.
Tips: This is a very short email marketing email with just a quick tip and your business info below. These are usually sent on a daily basis, but it is very easy to set up an autoresponder ahead of time so you don´t have to think about it too often.
Email marketing doesn´t require that you constantly send out email newsletters. Tailor your email marketing campaign to your website and your subscribers and you´ll be able to chance it or adjust the schedule to your target market.
http://emailmarketingjournal.com/2008/03/30/email-marketing