When developing a website with a particular CMS (Drupal, Joomla, Wordpress, etc.), we should consider the importance of installing and configuring a component that allows us to capture users' emails so that we can process them and then perform with them periodic shipments of news, promotions and other valuable data.
When a user, let us set a contact with him that transcends time, we are increasing the value of our website, as it not only generate contacts when users visit, but also when we have something important to communicate.
In this way, both parties are benefited (website owners and users) and it is assumed that only those users interested in the information provided leave your mail for information.
You must be a commitment of the owners of the website, just send information that may be useful for the newsletter subscribers, since the extent that the information is outdated, repetitive or invasive unsubscriptions be generated automatically, and that our brand is positioned negatively in public.
Each newsletter and actually each content offered on our website should be useful to users. In short we must focus all our actions as a service to users. There is always ask the question: "Is this useful and valuable?". Often they say that than to say useless things is better to say nothing, but in today's digital world say nothing is absent, so the generation of valuable content is extremely important.
Each platform has its specific modules CMS to capture emails and make sending newsletters. In turn, each company and each website has its specific needs.
It's in the marketing and web development professionals to know what is the best option.